CANBERRA, Australia — The United States announced plans Wednesday to establish a permanent military presence in Australia, part of a high-profile foreign policy shift toward Asia that is intended as a counterbalance to China’s growing power.

Starting next summer, the U.S. will send 250 Marines to bases here for six-month tours, eventually rotating 2,500 troops through the country. President Obama announced the partnership at a news conference with Australian Prime Minister Julia Gillard, describing it as a key step in his administration’s evolving emphasis on the Asia Pacific region as the U.S. winds down wars in Iraq and Afghanistan.

“We are here to stay,” Obama said. “This is a region of huge strategic importance to us.”

Administration officials said the Australian partnership will allow U.S. forces — called a Marine Air-Ground Task Force — access to the bases in the country’s Northern Territory, including one in Darwin, an area close to Southeast Asia that Obama will visit Thursday.

The Australian pact extends U.S. influence into Southeast Asia at a time of growing assertiveness in China. Obama is scheduled to deliver a speech to Australia’s parliament to lay out the United States’s renewed commitment, which is stirring anxiety in Beijing.

As part of the partnership, U.S. Marines will conduct training and amphibious exercises and the Air Force will station some of its aircraft at the Australian bases. The U.S. troops will be housed at Australian facilities; the United States will not create its own bases here, officials said.

Xinhua, China’s state news agency, greeted the plan with skepticism.

“China has always opposed any move to complicate the disputes with involvement of external forces, insisting bilateral dialogue is the best option,” the news service stated in a commentary shortly after Obama’s announcement. The United States “should appreciate the constructive role it is expected to play in the area.”

Obama had already drawn rebukes from Chinese media after criticizing China’s economic policies at a summit in Hawaii over the weekend. There, the president called on China to make its currency policy more flexible, to help balance trade and to respect intellectual property rights.

The United States also has grown alarmed by China’s increasingly confrontational stance in the South China Sea, a critical commercial shipping channel that is thought to contain valuable oil and minerals.

View Photo Gallery: Obama met with Australian Prime Minister Julia Gillard and announced a permanent military presence in Australia beginning next summer.

Even so, Obama said that the U.S. relationship with China is not a zero-sum game and that he could imagine a “win-win” scenario in which both nations prosper.

“The notion that we fear China is mistaken,” Obama said. Rather, the United States wants “a clear set of principles that all of us can abide by so all of us can succeed.”

But he added that China must understand that with its rise on the international stage comes increased responsibility.

If China does not respect international rules, Obama said, “we will send a clear message to them that we think that they need to be on track in terms of accepting the rules and responsibilities that come with being a world power.”

The repositioning of the troops comes as a bipartisan congressional committee is examining ways to slash at least $1.5 trillion from the nation’s ballooning budget deficit. If that committee, whose deliberations have so far been fruitless, fails to find a solution, defense spending would automatically be cut by a significant amount.

Obama pledged that he would not support cutting the defense budget in the Asia Pacific region.

“I’ve made very clear and will amplify in my speech to Parliament that even as we make a host of important fiscal decisions back home, this is right up there at the top of my priority list,” Obama said. “We will make sure we are able to fulfill our leadership role in the Asia Pacific region.”

Without dwelling on China, Obama and Gillard described the expanding alliance as a way to help provide military training to forces from Australia and Southeast Asian countries. U.S. troops also would be able to provide aid in natural disasters and humanitarian crises in the region.

“Southeast Asia is coming into its own,” said Danny Russel, Asia director at the National Security Council. “We are enhancing in Southeast Asia. As the region grows and changes, so too does our security and defense posture. ... These are countries that want U.S. and Australian help in building up their own capacities.”

Staff writer Keith Richburg in Beijing contributed to this report.

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