1970 and 1975. The airport was constrained by housing estates and although some work was done to keep it operational in the meantime, construction began on the new airport in 1975 and opened in 1981. Paya Lebar then closed to civil traffic, the IATA airport code of SIN and the ICAO airport code of WSSS were transferred to the newly opened civilian airport in Changi. Conversion to military use Singapore International Airport began to be gradually converted into a military air-force base from late 1967 onwards. During that year, an Air Movement Centre was constructed to handle passengers and cargo arriving on Republic of Singapore Air Force, and Ministry of Defence charter flights and foreign military aircraft. The original terminal building (painted green), maintenance hangar and control tower are retained. Access to terminal and hangars are off-limits closed off by a wired fence. It became a complete military airbase in 1981 when Singapore Changi Airport was opened and was subsequently renamed as Paya Lebar Air Base (PLAB) in the same year. Paya Lebar Air Base The air base currently houses aircraft such as the C-130 Hercules and two squadrons of F-15SG Strike Eagles. The flying squadrons are: 122 Squadron with 10 C-130 Hercules, 142 Squadron with 15 F-15SG Strike Eagles, 149 Squadron with >24 F-15SG Strike Eagles The support squadrons are: Air Logistics Squadron (ALS) Airfield Maintenance Squadron (AMS) Field Defence Squadron (FDS) Flying Support Squadron (FSS) Former squadrons based here are: 141 Squadron with F-5S/T, RF-5S 144 Squadron with F-5S/T Use by the United States Air Force Under Singapore's permission, the Paya Lebar Airbase is also used by various flying units of United States Air Force and United States Navy (including United States Marine Corps Aviation) as a strategic refuelling stopover and staging post/transit point; the base is also used permanently by the 497th Combat Training Squadron for other flight operations since 31 October 1991. Paya Lebar Air Base also plays host to USAF VIP aircraft as well, with regular visits by Air Force One, such as during President George W. Bush's two visits to Singapore in October 2003 and November 2006. Air Force Two carrying Vice-President Dick Cheney also made a refuelling stop and underwent minor repairs en route from Australia in 2007. The USAF Boeing 747-200 E-4B regularly lands at the base when the U.S. Secretary of Defense visits Singapore, as does the Boeing 757 C-32A that