Title: German declaration of war against the United States
Content:   On 11 December 1941, four days after the Japanese attack on Pearl Harbor and the United States declaration of war against the Japanese Empire, Nazi Germany declared war against the United States, in response to what was claimed to be a series of provocations by the United States government when the U.S. was still officially neutral during World War II. The decision to declare war was made by Adolf Hitler, apparently offhand, almost without consultation. It has been referred to as Hitler's "most puzzling" decision of World War II. Publicly, the formal declaration was made to American Chargé d'Affaires Leland B. Morris by German Foreign Minister Joachim von Ribbentrop in the latter's office. Later that day, the U.S. declared war on Germany, with Germany's action having eliminated any remaining meaningful domestic isolationist opposition to the U.S. joining the European war.
Title: United States declaration of war on Japan
Content:   On December 8, 1941, the United States Congress declared war on the Empire of Japan in response to that country's surprise attack on Pearl Harbor and declaration of war the prior day. It was formulated an hour after the Infamy Speech of President Franklin D. Roosevelt. Following the U.S. declaration, Japan's allies, Germany and Italy, declared war on the United States, bringing the United States fully into World War II.
Title: Attack on Pearl Harbor
Content:  day (December 8) the United States Congress declared war on Japan. On December 11, though they had no formal obligation to do so under the Tripartite Pact with Japan, Germany and Italy each declared war on the U.S., which responded with a declaration of war against Germany and Italy. There were numerous historical precedents for the unannounced military action by Japan, but the lack of any formal warning, particularly while peace negotiations were still apparently ongoing, led President Franklin D. Roosevelt to proclaim December 7, 1941, "a date which will live in infamy". Because the attack happened without a declaration of war and without explicit warning, the attack on Pearl Harbor was later judged in the Tokyo Trials to be a war crime.
Title: National Pearl Harbor Remembrance Day
Content:  Canada declared war on Japan within hours of the attack on Pearl Harbor, the first Western nation to do so. On December 8, the United States declared war on Japan and entered World War II on the side of the Allies. In a speech to Congress, President Franklin D. Roosevelt called the bombing of Pearl Harbor "a date which will live in infamy."
Title: Attack on Pearl Harbor
Content:  The day after the attack, Roosevelt delivered his famous Day of Infamy speech to a Joint Session of Congress, calling for a formal declaration of war on the Empire of Japan. Congress obliged his request less than an hour later. On December 11, Germany and Italy declared war on the United States, even though the Tripartite Pact did not require it. Congress issued a declaration of war against Germany and Italy later that same day. The United Kingdom had already been at war with Germany since September 1939 and with Italy since June 1940, and British Prime Minister Winston Churchill had promised to 
Title: United Kingdom declaration of war on Japan
Content:  On 7/8 December 1941, Japan attacked British and American territories in Southeast Asia and the Central Pacific with near-simultaneous offensives including an attack on the US fleet at Pearl Harbor. During negotiations with the administration of U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill had promised to declare war "within the hour" of a Japanese attack on the United States. News of the attack on Pearl Harbor reached London first. Realizing that President Roosevelt would go through the formal process of asking the United States Congress for a declaration of war, Churchill began making preparations to deliver the UK's own declaration of war immediately after Congress had formally declared war. After learning British territory had also been attacked, the British Prime Minister decided there was no need to wait for Congress to act and promptly summoned the Japanese Ambassador.
Title: Pacific War
Content:  Opposition to war in the US vanished after the attack. On 8 December, the United Kingdom, the United States, Canada, and the Netherlands declared war on Japan, followed by China and Australia the next day. Four days after Pearl Harbor, Germany and Italy declared war on the United States, drawing the country into a two-theater war. This is widely agreed to be a grand strategic blunder, as it abrogated both the benefit Germany gained by Japan's distraction of the US and the reduction in aid to Britain, which both Congress and Hitler had managed to avoid during over a year of mutual provocation, which would otherwise have resulted.
Title: No-No Boy
Content: "Are you willing to serve in the armed forces of the United States on combat duty wherever ordered?" ; "Will you swear unqualified allegiance to the United States of America and faithfully defend the United States from any or all attack by foreign or domestic forces, and forswear any form of allegiance or obedience to the Japanese emperor, to any other foreign government, power or organization?" On 7 December 1941, the Imperial Japanese Navy launched a surprise attack on Pearl Harbor, a U.S. naval base near Honolulu, Hawaii. The following day, December 8, the United States declared war on Japan. Many Americans rushed to join the military. After 
Title: Japanese declaration of war on the United States and the British Empire
Content:  The declaration of war by the Empire of Japan on the United States and the British Empire (米國及英國ニ對スル宣戰ノ詔書) was published on December 8, 1941 (Japan time; December 7 in the United States), 7.5 hours after Japanese forces started an attack on the United States naval base at Pearl Harbor and attacks on British forces in Malaya, Singapore, and Hong Kong. The declaration of war was printed on the front page of all Japanese newspapers' evening editions on December 8. The document was subsequently printed again on the eighth day of each month throughout the war (until Japan surrendered in 1945), to re-affirm the resolve for the war.
Title: Presidency of Franklin D. Roosevelt, third and fourth terms
Content:  on Pearl Harbor.  After Pearl Harbor, antiwar sentiment in the United States evaporated overnight. For the first time since the early 19th century, foreign policy became the top priority for the American public. Roosevelt called for war in his famous "Infamy Speech" to Congress, in which he said: "Yesterday, December 7, 1941 — a date which will live in infamy — the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan." On December 8, Congress voted almost unanimously to declare war against Japan. On December 11, 1941, Germany declared war on the United States, which responded in kind. Roosevelt portrayed the war 

Question: who declared war on the united states four days after pearl harbor?
Answer: Fascist Italy.
Nazi Germany.