“The U.S. needs to show the Chinese that they still have the power to overwhelm them, that they still can prevail if something really wrong happens,” said Huang Jing, a foreign affairs analyst and visiting professor at the National University of Singapore. “It’s a hedging policy.”

For the United States, the more muscular approach toward China has far-reaching implications, not just geopolitically but also economically. With Republicans at home calling for punitive measures against China for its currency and trade practices, Mr. Obama wants to appear strong in pressing Beijing. He made headway on an ambitious American plan to create a Pacific free trade zone, known as the Trans-Pacific Partnership, that, for now, would not include China.

For the Pentagon, which faces sweeping budget cuts in Congress, shifting its focus toward Asia provides a strong argument against cutting back its naval presence in the Pacific — something that Defense Secretary Leon E. Panetta explicitly ruled out in a recent visit to the region. He and Secretary of State Hillary Rodham Clinton have been prime proponents of the emphasis on Asia, with Mrs. Clinton shoring up old alliances, like those with Japan and South Korea, and cultivating new partners, like India and Indonesia.

Inside the White House, that emphasis has been reinforced by the president’s national security adviser, Thomas E. Donilon, who has argued that the United States needs to “rebalance” its strategic emphasis, from the combat theaters in Iraq and Afghanistan toward Asia, where he contends that Washington has put too few resources in recent years, because of its preoccupation with the two wars.

China has become the largest trading partner with most of the countries in the region, undercutting American economic influence. It also is projecting military power more broadly than at any other time in modern history. Its true military budget is not made public, but experts say it has at least tripled over the past decade, allowing China to strengthen a relatively weak maritime presence by building more modern ships that can operate with greater range and arming its first aircraft carrier. It has shown off what appears to be new stealth aircraft and has bought advanced weapons from Russia.