Singapore has asked that its future F-35s be stationed at an airbase within the United States not on the shortlist of bases preferred by the U.S. Air Force.

Comprising only 278 square miles, Singapore is limited in the amount of space it can devote to airports and air bases. The Republic of Singapore Air Force stations its units at eight locations within the country, with several detachments in the United States, France, Thailand and Australia.

With four F-35 purchased and an option to buy eight more, it has asked the U.S. Air Force to establish a "Foreign Military Sales Training Center" for F-35s at Luke Air Force Base, Ariz., where Singapore currently maintains its squadron of F-16 planes.

A new training center "in the continental United States which could accommodate up to 36 F-35 aircraft" is under consideration, Ann Sefanek, U.S. Air Force spokeswoman told Defense News.

"Based on negotiations with our foreign military sales customers as well as airspace and weather considerations, the Air Force is considering five candidate locations," she said.

The locations under consideration include Buckley AFB, Colo.; Fort Smith Airport, Ark.; Hulman Field, Ind; Joint Base San Antonio-Lackland, Texas, and Selfridge Air National Guard Base, Mich.

It remains a possibility that if Fort Smith receives the designation, Singapore's F-16s could be moved there.

Most of the bases on the shortlist have few or no permanently-stationed flying units, and none have the current capacity for F-35s, officials said.

Infrastructure improvements must be performed for any involvement, even on a rotational basis, for F-35s, the plane regarded as the foremost fighter plane in the world, they said.