US forces based at an airport in Kyrgyzstan are replacing their tent accommodation with more permanent buildings and said on Monday there was no end in sight to their mission in the Central Asian state.
The base was set up to support the war in neighbouring Afghanistan but has come under mild criticism from some locals, who see it as part of US militarisation of ex-Soviet Central Asia.
Kyrgyzstan has offered use of the base as long as military operations continue in Afghanistan.
"The tent city...is on the verge of its third winter and has not been renewed for some time," Captain Michael Johnson told reporters on Friday. "The tents are small and are only temporary accommodation."
"It will be here as long as it takes to complete the mission of combating terrorism throughout the world," added Captain Jason Decker on Monday, in response to emailed questions.
"The base is not permanent, nor is there any end in sight as long as the base serves the interests of both the American and Kyrgyz governments."
The new buildings at Manas, made of corrugated metal and looking like containers, are being put up at a cost of $60 million.
Around 2,000 US and European troops are based at Manas, a civilian airport outside the capital Bishkek, supporting military transport planes.
Its presence, which complements another US air base in Uzbekistan, rattled former imperial master Russia enough to set up its own air base at Kant, 30 km (20 miles) away last year - Moscow's first post-Soviet military outpost abroad.
"They are here for a long time," said Zamira Sydykova, editor of opposition newspaper Res Publica. "Central Asia is what they want, it's got little to do with Afghanistan."