China voiced misgivings about Obama's announcement of a de facto military base in Australia and has longstanding fears that its growing power could be hobbled by US influence. Obama acknowledged China's unease at what it sees as attempts by Washington to encircle it, pledging to seek greater cooperation with Beijing. The US military, turning its focus away from Iraq and Afghanistan, would be more broadly distributed in Asia, particularly Southeast Asia, more flexible and help build regional capacity, he told the Australian parliament. "As we end today's wars, I have directed my national security team to make our presence and missions in the Asia Pacific a top priority," Obama said in a major speech on Washington's vision for the Asia-Pacific region. "As a result, reductions in US defense spending will not -I repeat, will not - come at the expense of the Asia Pacific." He added: "We'll seek more opportunities for cooperation with Beijing, including greater communication between our militaries to promote understanding and avoid miscalculation." Nervous about China's growing clout, US allies such as Japan and South Korea have sought assurances from the United States that it would be a strong counterweight in the region. A first step in extending the US military reach into Southeast Asia will see US Marines, naval ships and aircraft deployed to northern Australia from 2012. That deployment to Australia, which by 2016 will reach a taskforce of 2,500 US troops, is small compared with the 28,000 troops stationed in South Korea and 50,000 in Japan. But the new de facto US base in Australia expands the direct US military presence in Asia, beyond South Korea and Japan and into Southeast Asia, an area where China has growing economic and strategic interests. It will also put more US troops, ships and aircraft much closer to the South China Sea over which Beijing has sovereignty disputes with several countries.