The US will base troops in Australia in the latest effort to boost its presence in the Asia-Pacific region and counter an ascendant China.

Speaking in Canberra, President Barack Obama said the Pentagon would station as many as 2,500 troops in Australia to help the US fulfil its “leadership role” in the region.

China’s neighbours and Washington are concerned about what they perceive as increasingly aggressive behaviour by the Chinese military in the disputed South China Sea. “It’s appropriate for us to make sure that . . . the security architecture of the region is updated for the 21st century,” said Mr Obama.

US troops have previously carried out joint training exercises in Australia with local forces and will not build a permanent base. The agreement calls for a contingent of 250 marines to arrive in Australia next year, with the total number rising to a maximum of 2,500 troops on six-month rotations. The shift comes as the US tries to reduce its reliance on its existing major bases in South Korea and Japan.

While China criticised the announcement, which comes at a time of improved US-Chinese military relations, its reaction was relatively restrained.

“It is debatable whether strengthening and expanding military alliances is a suitable move . . . at a time when we face a global economic downturn and when promoting development has become the consensus and the focus of the international community,” said Liu Weimin, foreign ministry spokesman.

State media were more direct in voicing concerns. Xinhua, the official news agency, said the US was “trying to get involved in a number of regional maritime disputes, some of which concern China’s sovereignty and territorial integrity”.