Consequences of the attack on Pearl Harbor The results of the attack on Pearl Harbor are many and significant . American response . On December 7 , 1941 , the Japanese launched a surprise attack on Pearl Harbor and hastened the entry of the United States into World War II on the side of the Allies . The day after the attack , President Franklin D . Roosevelt addressed a joint session of United States Congress . Roosevelt called December 7 " a date which will live in infamy " . Congress declared war on the Empire of Japan amid outrage at the attack and the late delivery of the note from the Japanese government breaking off relations with the U . S . government , actions considered treacherous . Pacifist Representative Jeannette Rankin , a Republican from Montana , cast the only dissenting vote . Roosevelt signed the declaration of war later the same day . Continuing to intensify its military mobilization , the U . S . government finished converting to a war economy , a process begun by provision of weapons and supplies to the Soviet Union and Great Britain . The Pearl Harbor attack immediately galvanized a divided nation into action . Public opinion had been moving towards support for entering the war during 1941 , but considerable opposition remained until the attack . Overnight , Americans united against Japan in response to calls to " Remember Pearl Harbor . " American solidarity in the war effort probably made possible the unconditional surrender position later taken by the Allied Powers . Some historians , among them Samuel Eliot Morison , believe the attack doomed Japan to defeat simply because it awakened the " sleeping giant " , regardless of whether the fuel depots or machine shops had been destroyed or even if the carriers had been caught in port and sunk . U . S . industrial and military capacity , once mobilized , was able to pour overwhelming resources into both the Pacific and Atlantic theaters . Others , such as Clay Blair , Jr . , and Mark Parillo believe Japanese trade protection was so incompetent that American submarines alone might have strangled Japan into defeat . The closest friend Roosevelt had in the developing Allied alliance , Sir Winston Churchill , stated that his first thought regarding American assistance to the United Kingdom was that " We have won the war " very soon after the United States had been attacked . Perceptions of treachery in the attack before a declaration of war sparked fears of sabotage or espionage by Japanese sympathizers residing in the U . S . , including citizens of Japanese descent and was a factor in the subsequent Japanese internment in the western United States . Other factors included misrepresentations of intelligence information ( none ) suggesting sabotage , notably by General John DeWitt , commanding general of Western Defense Command on the Pacific Coast , who had personal feelings against Japanese Americans . In February 1942 , Roosevelt signed United States Executive Order 9066 , requiring all Japanese Americans to submit themselves for an internment . Propaganda made repeated use of the attack , because its effect was enormous and impossible to counter . " Remember Pearl Harbor ! " became the watchwords of the war . The American government understated the damage inflicted , in hopes of preventing the Japanese from learning it , but the Japanese had , through surveillance , a good estimate . Japanese views . On December 8 , 1941 , the Empire of Japan declared war on the United States and the British Empire . The belated Japanese document discussed world peace and the disruptive actions of the United States and Great Britain . The document claimed all avenues for averting war had been exhausted by the Government of Japan . Although the Imperial Japanese government had made some effort to prepare their population for war " via " anti - U . S . propaganda , it appears most Japanese were surprised , apprehensive , and dismayed by the news they were now at war with the U . S . , a country many Japanese admired . Nevertheless , the people at home and overseas thereafter generally accepted their government ' s account of the attack and supported the war effort until their nation ' s surrender in 1945 . Japan ' s national leadership at the time appeared to have believed war between the U . S . and Japan had long been inevitable . In any case , Japanese - American relationships had already significantly deteriorated since Japan ' s invasion of China beginning in the early 1930s , of which the United States strongly disapproved . In 1942 , Saburō Kurusu , former Japanese ambassador to the United States , gave an address in which he talked about the " historical inevitability of the war of Greater East Asia . " He said war had been a response to Washington ' s longstanding aggression toward Japan . For example , provocations against Japan included the San Francisco School incident , ( the United States ' racist policies on Japanese immigrants ) , Naval Limitations Treaty , other Unequal treaties , the Nine Power Pact , constant economic pressure against Japan , culminating in the " belligerent " scrap metal and oil embargo in 1941 by the United States and Allied countries to contain and / or reverse the actions of the Empire of Japan especially in IndoChina during her expansion of influence and interests throughout Asia . In light of Japan ' s dependence on imported oil , the trade embargoes were especially significant . These pressures directly influenced Japan to go into alliance with Germany and Italy through the Tripartite Pact . According to Kurusu , because of these reasons , the Allies had already provoked war with Japan long before the attack at Pearl Harbor , and the United States was already preparing for war with Japan . Kurusu also states the United States was also looking for world domination , beyond just Asia , with " sinister designs " . Some of this view seems to have been shared by Adolf Hitler , when he called it one of the reasons Germany declared war on the United States . He also had mentioned European imperialism toward Japan many years before . Therefore , according to Kurusu , Japan had no choice but to defend herself and so should rapidly continue to militarize , bring Germany and Italy closer as allies and militarily combat the United States , Britain , and the Netherlands . Japan ' s leaders also saw themselves as justified in their conduct , believing that they were building the Greater East Asia Co - Prosperity Sphere . They also explained Japan had done everything possible to alleviate tension between the two nations . The decision to attack , at least for public presentation , was reluctant and forced on Japan . Of the Pearl Harbor attack itself , Kurusu said it came in direct response to a virtual ultimatum from the U . S . government , the Hull note , and so the surprise attack was not treacherous . Since the Japanese - American relationship already had hit its lowest point , there was no alternative ; in any case , had an acceptable settlement of differences been reached , the Carrier Striking Task Force could have been called back . Germany and Italy declare war . On December 11 , 1941 , Nazi Germany and Fascist Italy declared war on the United States , and the United States reciprocated , formally entering the war in Europe . German dictator Adolf Hitler and Italian dictator Benito Mussolini were under no obligation to declare war on the United States under the mutual defense terms of the Tripartite Pact . However , relations between the European Axis Powers and the United States had deteriorated since 1937 . Earlier in 1941 , the Germans learned of the U . S . military ' s contingency planning to get troops in Continental Europe by 1943 ; this was Rainbow Five , made public by sources unsympathetic to Roosevelt ' s New Deal , and published by the " Chicago Tribune " . Moreover , with Roosevelt ' s initiation of a Neutrality Patrol , which in fact also escorted British ships , as well as orders to U . S . Navy destroyer s first to actively report U - boat s , then " shoot on sight " , American neutrality was honored more in the breach than observance . Having been unaware of Japanese plans , Hitler was initially furious that the United States had been dragged into the war at a time when he had not yet acquired full control of continental Europe . Hitler , who had previously declared the Japanese " Honorary Aryan s " claimed that this is what happens when your allies are not Anglo - Saxons . However , he decided war with the United States was unavoidable , and the Pearl Harbor attack , the publication of Rainbow Five , and Roosevelt ' s post - Pearl Harbor address , which focused on European affairs as well as the situation with Japan , probably contributed to the declaration . Hitler underestimated American military production capacity , the nation ' s ability to fight on two fronts , and the time his own Operation Barbarossa would require . Similarly , the Nazis may have hoped the declaration of war , a showing of solidarity with Japan , would result in closer collaboration with the Japanese in Eurasia , particularly against the Soviet Union . Regardless of Hitler ' s reasons , the decision was an enormous strategic blunder and allowed the United States to enter the European war in support of the United Kingdom and the Allies without much public opposition . Author Ian Kershaw records Hitler ' s initial reaction to the attack , when he was first informed about it on the evening of 7 December at Führer Headquarters : " We can ' t lose the war at all . We now have an ally which has never been conquered in 3 , 000 years " . Well before the attack , in 1928 Hitler had confided in the text of his then - unpublished " Zweites Buch " that while the Soviet Union was the most important immediate foe that the Third Reich had to defeat , the United States was the most important long - term challenge to Nazi aims . Hitler awarded Imperial Japanese ambassador to Nazi Germany Hiroshi Ōshima the Grand Cross of the Order of the German Eagle in Gold ( 1st class ) after the attack , praising Japan for striking hard and without first declaring war . Canadian response . As a result of the Japanese attack on the Americans , the Prime Minister of the Dominion of Canada advised George VI , King of Canada , that a state of war should exist between Canada and Japan . In the late evening of December 7 , 1941 , the Canadian Prime Minister , W . L . Mackenzie King , announced the Cabinet ' s decision to declare war on Japan . The King approved Canada ' s declaration of war in the following proclamation issued on December 8 , 1941 . Whereas by and with the advice of our Privy Council for Canada we have signified our approval of the issue of a proclamation in the Canada Gazette declaring that a state of war with Japan exists and has existed in Canada as and from the 7th day of December 1941 . Now , therefore , we do hereby declare and proclaim that a state of war with Japan exists and has existed as and from the seventh day of December 1941 . Of all which our loving subjects and all others whom these presents may concern are hereby required to take notice and to govern themselves accordingly . Canada remained focused on the European theatre however , and following VE Day was still in the process of transitioning its military force for a campaign in east Asia and the western Pacific when VJ Day arrived . Investigations and blame . President Roosevelt appointed the Roberts Commission , headed by U . S . Supreme Court Justice Owen Roberts , to investigate and report facts and findings with respect to the attack on Pearl Harbor . It was the first of many official investigations ( nine in all ) . Both the Fleet commander , Rear Admiral Husband E . Kimmel , and the Army commander , Lieutenant General Walter Short ( the Army had been responsible for air defense of Hawaii , including Pearl Harbor , and for general defense of the islands against hostile attack ) , were relieved of their commands shortly thereafter . They were accused of " dereliction of duty " by the Roberts Commission for not making reasonable defensive preparations . None of the investigations conducted during the War , nor the Congressional investigation afterward , provided enough reason to reverse those actions . The decisions of the Navy and War Departments to relieve both was controversial at the time and has remained so . However , neither was court - martialed as would normally have been the result of dereliction of duty . On May 25 , 1999 , the U . S . Senate voted to recommend both officers be exonerated on all charges , citing " denial to Hawaii commanders of vital intelligence available in Washington " . A Joint Congressional Committee was also appointed , on September 14 , 1945 , to investigate the causes of the attack and subsequent disaster , and was convened on November 15 , 1945 . Rise of anti - Japanese sentiment and historical significance . The Japanese attack on Pearl Harbor coupled with their alliance with the Nazis and the ensuing war in the Pacific fueled anti - Japanese sentiment , racism , xenophobia , and anti - Axis sentiment in the Allied nations . Japanese , Japanese - Americans and Asians having a similar physical appearance were regarded with deep seated suspicion , distrust and hostility . The attack was viewed as having been conducted in an extremely underhanded way and also as a very " treacherous " or " sneaky attack " . Suspicions were further fueled by the " Niihau Incident " , as historian Gordon Prange stated " the rapidity with which the three resident Japanese went over to the pilot ' s cause " which troubled the Hawaiians . " The more pessimistic among them cited the Niihau incident as proof that no one could trust any Japanese , even if an American citizen , not to go over to Japan if it appeared expedient . " The attack , the subsequent declarations of war , and fear of " Fifth Column ists " resulted in internment of Japanese , German , and Italian populations in the United States and others , for instance the Japanese American internment , German American internment , Italian American internment , and Japanese Canadian internment . The attack resulted in the United States fighting the Germans and Italians among others in Europe and Japan in the Pacific . The consequences were world - changing . Prime Minister Winston Churchill knew that the survival of the British Empire depended on American aid , and since 1940 had begged Roosevelt to declare war . Churchill aide John Colville stated that the prime minister and American Ambassador John Gilbert Winant , who also supported the British , " sort of danced around the room together " as the United States would now enter the war , making a British victory likely . Churchill later wrote , " Being saturated and satiated with emotion and sensation , I went to bed and slept the sleep of the saved and thankful . " By opening the Pacific War , which ended in the unconditional surrender of Japan , it broke the power of an Asian check on Soviet expansion . The Allied victory in this war and subsequent U . S . emergence as a dominant world power , eclipsing Britain , have shaped international politics ever since . Pearl Harbor is generally regarded as an extraordinary event in American history , remembered as the first time since the War of 1812 America was attacked on its home soil by another country - with only the September 11 attacks almost 60 years later being of a similar catastrophic scale to Pearl Harbor . While this assertion is technically erroneous , as Hawaii was not a state at the time , it was widely regarded as such . It was the first decisive defeat for the United States in World War II . It has become synonymous with " surprise attack " ever since in the U . S . Unfortunately , the mistakes of intelligence collection , sharing , and analysis leading to the Japanese success at Pearl Harbor did not , in the end , lead to lessons . Perception of the attack today . Some Japanese today feel they were compelled to fight because of threats to their national interests and an embargo imposed by the United States , the United Kingdom and the Netherlands . The most important embargo was on oil on which its Navy and much of the economy was dependent . For example , the " Japan Times " , an English - language newspaper owned by one of the major news organizations in Japan ( Asahi Shimbun ) , ran numerous columns in the early 2000s ( decade ) echoing Kurusu ' s comments in reference to the Pearl Harbor attack . In putting the Pearl Harbor attack into context , Japanese writers repeatedly contrast the thousands of U . S . servicemen killed there with the hundreds of thousands of Japanese civilians killed in U . S . air attacks later in the War , even without mentioning the 1945 atomic bombings of Hiroshima and Nagasaki by the United States . However , in spite of the perceived inevitability of the war by many Japanese , many also believe the Pearl Harbor attack , although a tactical victory , was actually part of a seriously flawed strategy for engaging in war with the U . S . As one columnist eulogizes , " The Pearl Harbor attack was a brilliant tactic , but part of a strategy based on the belief that a spirit as firm as iron and as beautiful as cherry blossoms could overcome the materially wealthy United States . That strategy was flawed , and Japan ' s total defeat would follow . " In 1991 , the Japanese Foreign Ministry released a statement saying Japan had intended to make a formal declaration of war to the United States at 1 p . m . Washington time , 25 minutes before the attack at Pearl Harbor was scheduled to begin . This officially acknowledged something that had been publicly known for years . Diplomatic communications had been coordinated well in advance with the attack , but had failed delivery at the intended time . It appears the Japanese government was referring to the " 14 - part message " , which did not actually break off negotiations , let alone declare war , but did officially raise the possibility of a break in relations . However , because of various delays , the Japanese ambassador was unable to deliver this message until well after the attack had begun . Imperial Japanese military leaders appear to have had mixed feelings about the attack . Fleet Admiral Isoroku Yamamoto was unhappy about the botched timing of the breaking off of negotiations . He is on record as having said , in the previous year , " I can run wild for six months . . . after that , I have no expectation of success . " The reports of American reactions , terming it a " sneak attack " and " infamous behavior " , confirmed that the effect on American morale had been the opposite of intended . The first Prime Minister of Japan during World War II , Hideki Tōjō later wrote , " When reflecting upon it today , that the Pearl Harbor attack should have succeeded in achieving surprise seems a blessing from Heaven . " Yamamoto had said , regarding the imminent war with the United States , " Should hostilities once break out between Japan and the United States , it is not enough that we take Guam and the Philippines , nor even Hawaii and San Francisco . We would have to march into Washington and sign the treaty in the White House . I wonder if our politicians ( who speak so lightly of a Japanese - American war ) have confidence as to the outcome and are prepared to make the necessary sacrifices ? " Revisionism controversies . There are some revisionists in Japan who claim that the Attack on Pearl Harbor was a legitimate attack . These historical perspectives are often claimed by Japanese Shintoist and nationalists and have been criticized from both inside and outside of Japan . Analysis . Tactical implications . The attack was notable for its considerable destruction , as putting most of the U . S . battleships out of commission was regarded — in both navies and by most military observers worldwide — as a tremendous success for Japan . Influenced by the earlier Battle of Taranto , which pioneered the all - aircraft naval attack but resulted in far less damage and casualties , the Japanese struck against Pearl Harbor on a much larger scale than did the British at Taranto . The attack was a great shock to all the Allies in the Pacific Theater , and it was initially believed Pearl Harbor changed the balance of power , similar to how Taranto did the Mediterranean , both in the attackers ' favor . Three days later , with the sinking of " Prince of Wales " and " Repulse " off the coast of Malaya , British Prime Minister Winston Churchill exclaimed , " In all the war I never received a more direct shock . As I turned and twisted in bed the full horror of the news sank in upon me . There were no British or American capital ships in the Indian Ocean or the Pacific except the American survivors of Pearl Harbor who were hastening back to California . Over this vast expanse of waters Japan was supreme and we everywhere were weak and naked . " However , Pearl Harbor did not have as crippling an effect on American operations as initially thought . Unlike the close confines of the Mediterranean , the vast expanses of the Pacific limited the tactical value of battleships as a fleet in being . Furthermore , unlike new fast battleship s such as the , the slow battleships were incapable of operating with carrier task forces , so once repaired they were relegated to delivering pre - invasion bombardments during the island hopping offensive against Japanese - held islands . These Pearl Harbor veterans were later part of a force that defeated IJN battleships at the Battle of Surigao Strait , an engagement very lopsided in the USN ' s favor in any case . A major flaw of Japanese strategic thinking was a belief that the ultimate Pacific battle would be between battleships of both sides , in keeping with the doctrine of Captain Alfred Mahan . Seeing the decimation of battleships at the hands of aircraft , Yamamoto ( and his successors ) hoarded his battleships for a " decisive battle " that never happened , only committing a handful to the forefront of the Battles of Midway and Guadalcanal . One of the main Japanese objectives was to destroy the three American aircraft carrier s stationed in the Pacific , but they were not present : was returning from Wake , from Midway , and was under refit at Puget Sound Naval Shipyard . Had Japan sunk the American carriers , the U . S . would have sustained significant damage to the Pacific Fleet ' s ability to conduct offensive operations for a year or so ( given no further diversions from the Atlantic Fleet ) . As it was , the elimination of the battleships left the U . S . Navy with no choice but to place its faith in aircraft carriers and submarines — the very weapons with which the U . S . Navy halted and eventually reversed the Japanese advance . Battleships . Despite the perception of this battle as a devastating blow to America , only three ships were permanently lost to the U . S . Navy . These were the battleships , , and the old battleship ( then used as a target ship ) ; nevertheless , much usable material was salvaged from them , including the two aft main turrets from " Arizona " . The majority of each battleship ' s crews survived ; there were exceptions as heavy casualties resulted from " Arizona " magazine exploding and the " Oklahoma " capsizing . Four ships sunk during the attack were later raised and returned to duty , including the battleships , and . " California " and " West Virginia " had an effective torpedo - defense system which held up remarkably well , despite the weight of fire they had to endure , resulting in most of their crews being saved . and suffered relatively light damage , as did , which was in drydock at the time . Chester Nimitz said later , " It was God ' s mercy that our fleet was in Pearl Harbor on December 7 , 1941 . " Nimitz believed if Kimmel had discovered the Japanese approach to Pearl Harbor , he would have sortied to meet them . With the American carriers absent and Kimmel ' s battleships at a severe disadvantage to the Japanese carriers , the likely result would have been the sinking of the American battleships at sea in deep water , where they would have been lost forever with tremendous casualties ( up to twenty thousand dead ) , instead of in Pearl Harbor , where the crews could easily be rescued , and six battleships ultimately restored to duty . This was also the reaction of Joseph Rochefort , head of , when he remarked the attack was cheap at the price . Many of the surviving battleships were extensively refitted , including the replacement of their outdated secondary battery of anti - surface 5 " / 51 caliber gun s with more useful turreted dual - purpose 5 " / 38 caliber gun s , allowing them to better cope with the new tactical reality . Addition of modern radar to the salvaged vessels would give them a marked qualitative advantage over those of the IJN . The repaired U . S . battleships primarily provided fire support for amphibious landings . Their low speed was a liability to their deployment in the vast expanses of the Pacific , for instance they could not accompany the fleet carriers that had become the dominant combatants . Six of the Standard Type vessels participated in the last battleship versus battleship engagement in naval history , the Battle of Surigao Strait , where none of them were hit . During active duty , being well protected by escorts and air cover , none of the Pearl Harbor battleships suffered serious damage save for " Pennsylvania " which was permanently crippled by a torpedo in the closing stages of the war . Carriers . The attack on Pearl Harbor failed to sight , or destroy , any of the Pacific Fleet ' s aircraft carriers ; they had been designated as primary targets along with the battleships . The carriers " Lexington " and " Enterprise " were ferrying additional fighters to American bases on the islands of Wake and Midway . At the time of the Japanese attack , the US was expecting imminent war with Japan , beginning in any of several places , such as the Philippines or Allied bases in Borneo . Nagumo ' s hesitation , and failure to find and destroy the American carriers , may have been a product of his lack of faith in the attack plan , and of the fact he was a gunnery officer , not an aviator . In addition , Yamamoto ' s targeting priorities , placing battleships first in importance , reflected an out - of - date Mahan ian doctrine , and an inability to extrapolate from history , given the damage German submarines did to British trade in World War I . In the end , Japan achieved surprisingly little for all her daring and apparent success . Cruiser s , essential to carrier task forces later in the war , had been considered tertiary targets and only three suffered damage . Of 27 destroyer s present , only two were lost : and were total losses as ships , but their machinery was salvaged and fitted into new hulls , retaining their original names , while " Shaw " was raised and returned to service . Shore installations . Tank farms , containing 140 million U . S . gallons ( 530 million liters ) of bunker oil , were unscathed , providing a ready source of fuel for American fleets at the submarine base . About this missed opportunity , Admiral Chester Nimitz would later say , " Had the Japanese destroyed the oil , it would have prolonged the war another two years . " These were vital to the initial phase of the war , and to commerce raiding throughout , and illustrate the deficiencies of Japanese planning for the attack . The Navy Yard , critical to ship maintenance , and repair of ships damaged in the attack was undamaged . The engineering and initial repair shops , as well as the torpedo store , were intact . Other items of base infrastructure and operation , such as power generation , continued to operate normally . Also critical to the way the Pacific War was actually fought was the cryptanalysis unit , Station , located in the basement of the old Administration Building . It was undamaged and even benefited by gaining staff from unemployed ship ' s bands . The Army Air Force ' s loss of aircraft must be balanced against the fact that many of them were obsolete , such as the P - 40 ' s predecessor , the P - 36 . Japan might have achieved a good deal more with not much additional effort or loss . Charts . Of the 22 Japanese ships that took part in the attack , only one survived the war . As of 2006 , the only U . S . ships in Pearl Harbor during the attack still remaining afloat are the Coast Guard Cutter " Taney " and the yard tug . Both remained active over 50 years after the attack and have been designated museum ships . Strategic implications . A common view is that the Japanese fell victim to victory disease because of the perceived ease of their first victories . It has also been stated by the Japanese military commanders and politicians who visited and lived in the United States , that their leadership ( mostly military personnel ) took the war with the United States relatively lightly , compared to them . For instance , Admiral Yamamoto and General Tadamichi Kuribayashi expressed concerns about the greater industrial power of the United States . The politics of a " Europe First " strategy , loss of air cover over Pearl Harbor , and subsequent loss of the Philippines , meant the U . S . Army and Army Air Corps were unable to play a significant role in the Pacific War for several months . Japan was temporarily free of worries about the major rival Pacific naval power , which was at least part of the intention for the attack . Because Australian , New Zealand , Dutch and most British forces were already in Europe , Japan conquered nearly all of Southeast Asia , the Southwest Pacific , and extended her reach far into the Indian Ocean , without significant interference . The various Japanese advances were a nearly complete tactical success . In the long term , the attack on Pearl Harbor was a grand strategic blunder for Japan . Indeed , Admiral Yamamoto , who conceived it , predicted even success here could not win a war with the United States , because American productive capacity was too large . It spurred the United States into a determination to fight to complete victory . The war resulted in the destruction of the Japanese armed forces , the occupation of the home islands ( a state never before achieved in Japan ' s history ) , and the loss of Okinawa and the Ryukyu Islands to the United States until 1972 , while the Soviet Russian re - annexation of the Kurile islands and Sakhalin Island ' s southern part , and the restoration of Formosa ( Taiwan ) to the Republic of China , and the loss of Korea have not been reversed to this day .