U - Tapao Royal Thai Navy Airfield U - Tapao Royal Thai Navy Airfield is a military airfield of the Royal Thai Navy located approximately southeast of Bangkok , near Sattahip on the Gulf of Siam . It is serves as the home of the Royal Thai Navy First Air Wing . Name . U - Tapao ( ) is a compound of cradle and trade winds , and derives from the site having once been a shipyard for construction of ruea - tapao ( ) , a type of argosy resembling a Qing Dynasty junk . Units . U - Tapao is the main flying base for the Royal Thai Navy . Squadrons based there include : Two squadrons are dormant Current uses . For several years , beginning in 1981 , U - Tapao has hosted parts of Operation Cobra Gold – the largest U . S . military peacetime exercise in the Pacific – jointly involving U . S . , Singaporean , and Thai forces , and designed to build ties between the nations and promote interoperability between their military components . Thailand is an important element in the Pentagon ' s new strategy of " forward positioning " . Despite Thailand ' s neutrality on the 2003 invasion of Iraq , the Thai government allowed U - Tapao to be used by American warplanes flying into combat in Iraq , as it had earlier done during the war in Afghanistan . In addition , U - Tapao may be where Al Qaeda operative Abu Zubaydah was interrogated , according to some retired American intelligence officials . A multinational force headquarters was established at U - Tapao to coordinate humanitarian aid for the Sumatran Tsunami of 26 December 2004 . On 7 May 2008 , in the aftermath of Cyclone Nargis , Thai C - 130 transports were permitted to land at Yangon International Airport in Burma , carrying drinking water and construction material . From 12 to 20 May , USAID and the U . S . Department of Defense ( DOD ) coordinated the delivery of nearly $ 1 . 2 million of U . S . relief commodities to Yangon on 36 DOD C - 130 flights , with supplies sufficient to provide assistance to more than 113 , 000 beneficiaries . The DOD efforts were under the direction of Joint Task Force Caring Response . As of 26 June 2008 , United States assistance directed by the USAID DART ( Disaster Assistance Response Team ) stationed in Thailand , had totaled $ 41 , 169 , 769 . Units involved were the 36th Airlift Squadron ( 36 AS ) of the 374th Airlift Wing ( 374 AW ) from Yokota Air Base , Japan , flying C - 130H Hercules ; and Marine Aerial Refueler Transport Squadron 152 ( VMGR - 152 ) from Marine Corps Air Station Futenma , Okinawa , Japan , flying the Lockheed Martin KC - 130 R and the newer KC - 130J . In 2012 , a proposal for the United States National Aeronautics and Space Administration ( NASA ) to use the military capacities to support weather research was canceled . American use of U - Tapao during the Vietnam War . Prior to 1965 , U - Tapao was a small Royal Thai Navy airfield . At Don Muang Air Base near Bangkok the USAF had stationed KC - 135 air refueling tankers from Strategic Air Command ( SAC ) for refueling tactical combat aircraft over the skies of Indochina . Although Thailand was an active participant in the war , with a token ground force deployed to the Republic of Vietnam and a more substantial involvement in Laos , the visibility of the large USAF Boeing tankers in its capital was causing political embarrassment to the Thai government . In June 1965 , The B - 52F was first used in the Vietnam War . B - 52F aircraft taken from the 7th and 320th Bomb Wings were sent to bomb suspected Viet Cong enclaves in South Vietnam . The B - 52Fs were stationed at Andersen AFB on Guam , the operation being supported by KC - 135As stationed at Kadena AB on Okinawa . By November 1965 , the B - 52s were able to support the 1st Air Cavalry Division in mopping up operations near Pleiku . The Seventh Air Force ( PACAF ) wanted to have additional B - 52s missions flown into the war zone ; however , the B - 52 missions from Andersen , as well as from Kadena AB , Okinawa , required long mission times and air refueling . Concerns about base security with having the aircraft based in South Vietnam led to the change of mission at Tuy Hoa Air Base from that of basing B - 52s there to one of a tactical air base . It was decided that , as the base at U - Tapao was being established as a KC - 135 tanker base to move them out of Don Muang , to also base the B - 52s there where they could fly unrefuelled throughout both North and South Vietnam . The construction of U - Tapao Royal Thai Navy Airfield began in October 1965 and was completed slightly more than two years later . The 11 , 000 - foot runway was opened on 6 July 1966 and the first aircraft to land was a Royal Thai Air Force HH - 16 Helicopter , then a USAF C - 130 Hercules cargo aircraft . With the completion of U - Tapao , most American forces were transferred from Don Muang , and U - Tapao RTNAF became a front - line facility of the United States Air Force in Thailand during the Vietnam War from 1966 through 1975 . The USAF forces at U - Tapao were under the command of the United States Strategic Air Command ( SAC ) . The APO for U - Tapao was APO San Francisco , 96330 4258th Strategic Wing . The 4258th Strategic Wing ( SAC ) was activated in June 1966 at U - Tapao under the 3rd Air Division , Andersen AFB , Guam . The wing was charged with the responsibility of supporting refueling requirements of USAF fighter aircraft in Southeast Asia , plus conducting bombing missions on a daily basis . Steadily progressing and adding to the mission , U - Tapao welcomed its first complement of KC - 135 tankers in August 1966 . By September , the base was supporting 15 tankers . From 1966 to 1970 , 4258th wing tankers flew over 50 , 000 sorties from U - Tapao . On 10 April 1967 , three B - 52 bombers landed at U - Tapao following a bombing mission over Vietnam . The very next day , B - 52 operations were initiated at U - Tapao . Under the operational nickname “ Arc Light ” , wing bombers flew over 35 , 000 strikes against the communist enemy from 1967 to 1970 . B - 52 Missions from U - Tapao . Although the B - 52F carried out the first B - 52 missions in Southeast Asia , less than 6 months later , the Air Force decided to convert most of its B - 52Ds to conventional warfare capability for service in Southeast Asia . Modifications were needed to give the B - 52D the ability to carry a significantly larger load of conventional bombs , which led to the Big Belly project that was begun in December 1965 . The project increased the internal bomb capacity from just 27 weapons to a maximum of 84 500 - lb Mk 82 or 42 750 lb M117 conventional bombs . This was done by careful rearrangement of internal equipment , and did not change the outside of the aircraft . In addition , a further 24 bombs of either type could be carried on modified underwing bomb racks ( originally designed for the carrying of AGM - 28 Hound Dog cruise missiles and fitted with I - beam rack adapters and a pair of multiple ejection racks ) , bringing the maximum payload to of bombs , about more than the capacity of the B - 52F . Between 1966 and 1975 , SAC B - 52 squadrons ( mostly B - 52D , but some B - 52G ) were rotated to combat duty in Southeast Asia . SAC crews who ordinarily would have been assigned to the B - 52G or H models were sent through an intensive two - week course , mostly on the B - 52D , making them eligible for duty in Southeast Asia . Camouflage paint in tan and two shades of green , still with white undersides , was applied to B - 52s when other USAF aircraft were adopting camouflage . B - 52Ds assigned to combat duty in Vietnam were painted in a modified camouflage scheme with the undersides , lower fuselage , and both sides of the vertical fin being painted in a glossy black . The USAF serial number was painted in red on the fin . The B - 52s would fly on a mission in groups of three , and three B - 52s could cut a swath miles long through the jungle , with the aircraft flying so high that the enemy had no idea they were under attack until the bombs began to hit . The shock of such concentrated high explosive was tremendous , with tales of scouts on the ground finding entire enemy units dead , without a mark on them , simply killed by concussion . Survivors of such attacks were demoralized or shellshocked . The bomber would also ultimately take on the jungle tunnel complexes that frustrated the Americans for so long , carpeting them with heavy bombs fitted with delayed action fuzes . The bombs would bury themselves deeply into the ground and then detonate , caving in the tunnels . However , the B - 52 itself could not really do much to change the course of the war , since the Johnson Administration , hobbled by fears of a " wider war " , failed to devise any effective military and political strategy to deal with the insurgency in Vietnam . The B - 52 was devastating when targets could be found , but in many cases the enemy was elusive and all the bombers accomplished was to level stretches of jungle and kill lots of monkeys . It has been debated ever since whether there was any rational way to win the conflict . Optimists claim the often absurd " rules of engagement " for attacks on the enemy , imposed from the top by US president Lyndon Johnson and his defense secretary Robert McNamara , crippled the ability of US forces to fight . The Johnson Administration tried to fine - tune the war , selectively increasing the pressure to try to force the North Vietnamese to negotiate , while avoiding any major escalation . Known SAC units at U - Tapao . U - Tapao was initially more of a forward field than it was a main operating base , with responsibility for scheduling missions still remaining at Andersen AFB . Small numbers of aircraft were drawn from each SAC B - 52D unit to support the effort in Thailand . Known squadrons which deployed B - 52 and KC - 135 aircraft and crews to U - Tapao were : These units deployed usually on 90 days tours . Sapper attack . On 10 January 1972 , enemy insurgents attempted to destroy B - 52 aircraft via a ' Sapper Attack ' wherin ' satchel charges ' were placed in or near aircraft . The estimate of attackers varies from 3 to 10 individuals , with off base fire support . Gunfire was exchanged and a number of explosions occurred . This is the only officially reported attack against U - Tapao , although eyewitness reports reflect a number of mortar attacks and numerous incidents of sabotage . Khe Sanh . One of the most important actions of the B - 52 in the Vietnam War was during the siege of Khe Sanh in early 1968 . The North Vietnam ese surrounded an isolated US Marine outpost there and began conducting a methodical siege , building trenchworks that crept closer to the outpost while the two sides traded fire . Concentrated bombardments by B - 52s with unbroken waves of six aircraft , attacking every three hours , dropped bombs as close as from the perimeter of the outpost , cratered out the North Vietnamese entrenchments and inflicted heavy casualties , forcing them to give up the siege . 2 , 548 B - 52 sorties were flown under the appropriately - named OPERATION NIAGARA in support of the defense of Khe Sanh , dropping a total of 54 , 129 tonnes ( 59 , 542 tons ) of bombs . Raids were not only flown out of Andersen AFB and U Tapao , but from Kadena Air Base on Okinawa , where B - 52Ds had been sent to counter aggressive North Korean moves . The fact that Kadena was performing raids on Southeast Asia was kept secret to keep from inflaming Japanese public opinion . The Japanese had been on the receiving end of American heavy bomber strikes only a few decades before , and it took no great wisdom to realize they would find even passive involvement in such activities very disagreeable . While the bombers were formally restricted from dropping their bombs any closer than a kilometer from the Khe Sanh base perimeter , the Marines lied to the aircrews and sometimes put them at or even closer . When the enemy finally withdrew , Americans scouting out the abandoned North Vietnamese positions found a moonscape of craters with no trees standing , littered with hundreds of enemy dead . Raids in Cambodia . Beginning in March 1969 , B - 52s were performing raids not only on South Vietnam and Laos , but on Cambodia as well . The Nixon Administration had approved this expansion of the war not long after entering office in the spring of 1969 . These Cambodian bombing raids were initially kept secret , and both SAC and Defense Department records were falsified to report that the targets were actually in South Vietnam . The Cambodian raids were actually carried out at night under the direction of ground units using the MSQ - 77 radar , which guided the bombers to the release point and told them the precise moment to release their bombs . This made the deception easier , since even the crew members aboard the bombers did not have to know what country they were bombing . However , the specific flight coordinates ( longitude and latitude ) of the points of bomb release were noted in the navigator ' s logs at the end of each mission , and a simple check of the map could tell the crews which country they were bombing . The Cambodian effort would eventually turn out to be something of a fiasco . It is unclear how much damage was done to North Vietnamese Army in their enclaves there , but it is perfectly clear that the raids did much to destabilize the Cambodian government , eventually leading to the downfall of the Norodom Sihanouk government and the rise of the notoriously savage Khmer Rouge regime . Raids in North Vietnam . U - Tapao based B - 52s carried out Operation Arc Light attacks on North Vietnam , although at first only the very southernmost part near the Demilitarized Zone was hit . The B - 52s generally avoided North Vietnamese airspace at this stage in the war , lest one of them fall victim to a Surface - to - air missile ( SAM ) , which would have been a propaganda coup for North Vietnam and extremely embarrassing to the Defense Department . 307th Strategic Wing . On 21 January 1970 , the 4258th SW was redesignated as the 307th Strategic Wing . The 307th was the only regular Air Force SAC Wing stationed in Southeast Asia . The 307th was under the command and control of Eighth Air Force , based at Andersen AFB , Guam . Four provisional squadrons were organized under the 307th : In addition , two four - digit bomb squadrons ( 4180th , 4181st ) were assigned , but were not operational . Operation Linebacker . The Vietnamization of the Vietnam war was put to the test in the spring of 1972 , when the North Vietnamese launched a full - scale offensive across the Vietnamese Demilitarized Zone ( DMZ ) , supported by tanks and heavy artillery . By this time , the US was no longer in the forefront of the ground war , with South Vietnamese units taking the lead . However , America was still providing air power , and US combat planes flew vast numbers of strikes , smashing the North Vietnamese . Although there had been no campaign of strikes into North Vietnam since the end of ROLLING THUNDER , the Nixon Administration ordered a new air offensive , initially codenamed FREEDOM TRAIN and then becoming LINEBACKER , with relatively few restrictions on targets that could be hit . The B - 52s conducted a limited number of strikes against North Vietnam as part of the spring 1972 invasion , though most of their sorties were on Arc Light missions elsewhere . The North Vietnamese offensive was crushed , but the strikes on North Vietnam continued , only winding down in October , ahead of the United States presidential election , 1972 . Richard Nixon was reelected , and the attacks quickly ramped up again in November . In late 1972 , the B - 52 was confronted with surface to air missile ( SAM ) defenses , it was only a matter of time before the North Vietnamese got lucky . That finally happened on 22 November 1972 , when a B - 52D was damaged by an SA - 2 SAM in a raid on Vinh , an important rail center in the southern part of North Vietnam . The bomber ' s pilot managed to get the burning aircraft back to Thailand before the crew bailed out , leaving the aircraft to crash . All the crew were recovered safely . Operation Linebacker II . Since 1967 , the Americans had been negotiating with North Vietnam to allow the US to withdraw from Vietnam in peace , and get back prisoners of war ( POWs ) rotting in North Vietnamese POW camps . The negotiations had been a frustrating , quarrelsome joke for years , and in late 1972 the Nixon Administration finally ran out of patience and ordered an all - out air offensive against North Vietnam . The bombing raids began on 18 December 1972 . The new campaign , codenamed LINEBACKER II , involved very heavy attacks by almost every strike aircraft the US had in the theater , with the B - 52 playing a prominent role . The initial plan scheduled attacks for three days . Along with heavy strikes by Air Force and Navy tactical aircraft , 129 B - 52s in 3 waves ( approx 4 hours apart ) from the 307th Strategic Wing at U - Tapao RTNAF , Thailand and B - 52Ds and −52Gs of both wings based at Andersen AFB , Guam , the 43d Strategic Wing and the 72 Strategic Wing ( Provisional ) . These went into battle on the night of 18 December , with the crews under strict orders to fly straight and level on approach and not release bombs unless they were sure they were on the target . The brass didn ' t want reports showing up in the news media that they had bombed a hospital by mistake . The B - 52s were assisted by F - 4 Phantom s laying down corridors of chaff and providing Barrier Combat air patrol ( BARCAP ) against North Vietnamese MiG - 17 s ; Lockheed EC - 121 College Eye radar aircraft tracking the comings and goings of enemy fighters ; F - 105 Thunderchief s performing " Wild Weasel " attacks on surface to air missile ( SAM ) sites ; and EB - 66 Destroyer jamming aircraft blinding enemy radars and communications . Three B - 52s were lost on the 18th . 93 flew raids on the 19th , with no losses , but the strike plan was basically the same as it had been the day before . Though radar jamming denied SAM crews targeting data , North Vietnamese noticed the pattern . 99 B - 52s flew strikes on 20 December , and SAM sites fired their missiles in a " shotgun pattern . Six aircraft were blown out of the sky . B - 52 crews grew increasingly frustrated with the predictable tactics , knowing they would lead to trouble sooner rather than later , and the result of the losses was an outburst of protest and anger . The crews were perfectly willing to fly combat missions , but they were not happy about dead - headed military bureaucracy setting them up like ducks in a shooting gallery . The Air Force has never been very specific on what exactly happened , some sources claiming that they had a near - mutiny on their hands , but it is clear that the brass decided to sit down and work on getting their house in order . The Andersen AFB based B - 52G were taking a disproportionate share of the losses . The " wet wing " of the B - 52G made it more vulnerable to battle damage , as did the fact that not all of the B - 52Gs had the same level of countermeasures fit as the B - 52D . This situation was made all the more ironic because the B - 52G , with no capability of carrying bombs on its external pylons , could only carry about a quarter the conventional bombload of the B - 52D . The B - 52G could carry 1 rack with 27 MK - 82 500 pound bomb s , where the B - 52D could carry 3 racks for a total of 84 500 - lb Mk 82 or 42 750 lb M117 conventional bombs internal and 24 external bombs made for a total of 108 bombs . All Andersen Linebacker II missions required at least 1 ( and some missions required 2 ) aerial refueling s , supported by the 376th Strategic Wing based at Kadena AB . The B - 52Gs were ordered to stand down for two days while fixes were hurriedly implemented . 30 B - 52Ds out of U Tapao flew strikes on 21 December , but the results were still bad , with two bombers lost . The next night , the 22nd , 30 B - 52Ds came back again , but this time their attacks were performed from unpredictable directions , and there were no losses . Strikes were made on SAM sites to help wear down the defenses for later . The same approach , 30 bombers using unpredictable tactics , was repeated on the 23rd and 24th , once again with no losses . The raids were called off on Christmas Day as a good - will gesture , to which there was no response . The Air Force hadn ' t been expecting any different , and had spent all of Christmas Day setting up an operation that would take advantage of all the lessons that had been learned in the campaign . On 26 December , a total of 120 B - 52s performed raids , with 113 reaching their targets nearly simultaneously , all dropping their bombs within a space of 15 minutes , overwhelming the defenses . Two B - 52s were lost , but the North Vietnamese were beginning to run out of SAMs and their air defenses were wobbly . 60 B - 52s came back on the 27th , with two lost , but this was the last gasp of the defenders . 60 bombers hit again on the 28th and 29th , with no losses . The North Vietnamese agreed to negotiate on 29 December , and the B - 52s stopped their strikes against North Vietnam . In 11 days of concentrated bombing , B - 52s had performed 729 sorties and dropped 13 , 640 tonnes ( 15 , 000 tons ) of bombs . The North Vietnamese claimed that almost 1 , 400 civilians were killed , though the fact that there weren ' t more was a testimony to the accuracy of the strikes , given the staggering amount of explosives dropped . The campaign was expensive , and not merely in financial terms . 15 B - 52s were lost , with 33 of their aircrew killed or missing in action . While the Air Force justifiably regarded the B - 52 losses as severe , in one minor compensation , North Vietnamese SAMs had hardly proven effective , with a kill ratio of only 2 % to 3 % of the number of SAMs fired . They had scored the kills by simply flooding the sky with SAMs , and the Soviet Union was not happy about the poor showing of their weapons . In another small compensation , North Vietnamese MiG interceptors proved completely ineffective at taking on the B - 52s according to US statistics , the MiGs scored no kills and two of them were claimed shot down by the " quad - fifties " in B - 52 tail turrets . However , North Vietnamese records insist that two of the Buffs shot down were MiG kills . Although the unrestricted bombing campaign was referred to by critics as " an attempt to pillage and burn the enemy to the conference table " , LINEBACKER II , sometimes called the " Eleven - Day War " , was believed by many as devastatingly successful in achieving its goals . Henry Kissinger contrasted the extremely uncooperative attitude of North Vietnamese negotiators before the raids with the great willingness to talk after them , and concluded : " These facts have to be analyzed by each person for himself . " It is tempting to speculate that such a ruthless air campaign earlier in the war might have changed its course considerably , but history is not a controlled experiment and speculation is all that it is . Howerer , the North Vietnamese account ' s was that the operation did not achieved it supposed goals . Vo Nguyen Giap ' s claim that the US had boycotted the negotiation process , and Operation Linebacker II was an attempt to force the Vietnamese into accepting their own " peace solution " . He ' s also attributed the small amount of civilian deaths , not to the bombing ' s accuracy , but the fact that Hanoi was almost emptied . In the end , the Paris Peace Accord was signed with terms favorable to them , and it takes Nixon to force Thieu , president of South Vietnam into signing it with threat of a possible coup against him . A cease - fire was signed on 23 January 1973 , with American POWs being flown out of Hanoi beginning on 18 March . However , the B - 52 ' s war was not quite over , with Arc Light strikes on Laos continuing into April and on Cambodia into August . The 307th SW ended all combat operations on 14 August 1973 . 1975 South Vietnamese collapse . In the two years following the 1973 Paris Peace Accords and the War Powers Act the North Vietnamese army underwent a massive rebuilding to recoup the losses suffered during the failed 1972 Easter Offensive . By the spring of 1975 , the North Vietnamese Army had grown to be the fifth largest in the world , and in late December 1974 had begun their drive towards Saigon . By the end of March 1975 , North Vietnamese troops had taken over several key cities , either because the ARVN forces were unequipped and undermanned , or because they had fled from the approaching enemy . By the second week of April , the situation had deteriorated to the point that most of South Vietnam was under the control of the North Vietnamese Army . A Congressional delegation had visited South Vietnam and was unable to convince President Ford to provide more aid . President Ford stated in a speech on 23 April that the Vietnam War " . . was finished " . An estimated 8 , 000 U . S . and third - country nationals needed to be evacuated from Saigon and the shrinking government - controlled region of South Vietnam , along with thousands of Vietnamese who had worked for the United States during the war who would be in dire straits under the Communists . The evacuation of Saigon was originally code - named Talon Vice and called for the evacuation of personnel via commercial aircraft from Tan Son Nhut Airport and other locations . The plan called for the ARVN to provide crowd control and to secure the evacuation areas . However as the situation deteriorated rapidly in South Vietnam , the plan was changed to use rooftops as helicopter landing pads for evacuating personnel . The evacuation plans were completed by 18 April and the name was changed to Operation Frequent Wind . U - Tapao Airfield was used as a jumping - off point by the USAF with eight CH - 53 and two HH - 53 " Sea Stallion " helicopters . Additional helicopters were standing by on board the USS " Midway " , and at the Nakhon Phanom and Ubon air bases . Korat placed a force of F - 4 ' s , A - 7 ' s and AC - 130 ' s on alert . Udon discontinued its training flights and put its F - 4 fighters on alert for combat missions over South Vietnam to support the evacuation . On 25 April South Vietnamese president Thieu fled the country , and the final collapse of the South Vietnamese government was imminent . Aircraft started to arrive at U - Tapao in South Vietnamese markings . They arrived all that day and the next several days . C - 119 ' s , C - 130 ' s , C - 47 ' s were filled to capacity with men , women and children . After their arrival , the Vietnamese were sequestered in tents near the runway . The adjacent parking ramps and grassy areas were being filled to capacity with South Vietnamese helicopters and aircraft , including many F - 5E / F aircraft which were just delivered to South Vietnam in the previous few months . By 29 April the North Vietnamese had brought in Anti - Aircraft Artillery ( AAA ) and mobile Surface - To - Air Missiles ( SAM ) to the Saigon area . Mortar and artillery rounds were impacting at Tan Son Nhut Air Base severely disrupting the evacuation activities . At the US Embassy , Saigon , Marine guards shut off the electricity to the elevators and exploded tear gas canisters as they went to the roof to join the evacuees . The last helicopter left the embassy at 7 : 53 am On 29 April , Douglas VC - 47A 084 of Air America crashed on landing . The aircraft was on a flight from Tan Son Nhat International Airport , Saigon , Vietnam . On 30 April South Vietnam surrendered . A handful of South Vietnamese Air Force aircraft that had been performing last - ditch air strikes completed their missions and flew on to U - Tapao . On 2 May the last air rescue helicopters returned to Nakhon Phanom . The war in Vietnam was over . Mayagüez incident . On 12 May 1975 , less than two weeks after the fall of Saigon , a unit of the Cambodian Khmer Rouge navy seized the American - flagged container ship SS Mayaguez , taking the crew hostage . U - Tapao Airfield served as a staging point for United States Marines which deployed to U Tapao and assaulted Koh Tang Island aboard Air Force CH - 53 s of the 21st Special Operations Squadron and HH - 53 s of the 40th Aerospace Rescue and Recovery Squadron , hitting the beach at sunrise on the 15 May in the Air Force ’ s first - ever helicopter - assault operation . However , virtually everything that could go wrong did . The Marines and helicopter crews never received the good intelligence available about the island ’ s defenders ; they went in expecting 18 to 40 lightly armed militia but instead found a reinforced battalion of elite Khmer Rouge naval infantry . The Cambodians shot down three of the first four CH - 53 helicopters to approach the island , one of them carrying the Marine forward air controller ( FAC ) team ; the fourth was badly damaged and forced to abort . For hours , Air Force A - 7 ' s from Korat RTAFB provided fire support failed to find the marines , let alone support them . The Marines hung on by a thread while the remaining helicopters of the assault wave fed in reinforcements ; the enemy badly shot up most of the remaining seven helicopters – only three landed in commission at U Tapao . A boarding party , transferred to the USS Harold E . Holt ( FF - 1074 ) by helicopter , seized the Mayaguez , only to find the ship deserted ; the Cambodians had taken its crew to the mainland two days earlier . When the extraction began , only five helicopters were available , and one was quickly shot up and put out of commission . Maintenance provided one more as the rescue proceeded , providing a razor - thin margin of success . USAF withdrawal . U - Tapao had come a long way since the first American personnel arrived in the mid - 1960s . With the fall of both Cambodia and South Vietnam in the spring of 1975 , the political climate between Washington and Bangkok had become very sour , and the Royal Thai Government wanted the USAF out of Thailand by the end of the year . In response , the USAF implemented Palace Lightning which was the plan by which the USAF would withdraw its aircraft and personnel from Thailand . The SAC units left in December 1975 ; however , the base remained under American control until it formally handed to the Thai government on 13 June 1976 .