In November 2011, with the Arab Spring uprisings in full tilt and Europe rocked by a debt crisis, President Barack Obama flew to Asia to promote a shift of America's military, diplomatic and business assets to the region. His then Secretary of State, Hillary Clinton, declared in the same year that the 21st century would be "America's Pacific century."
Fast-forward to today: as Obama flies to Asia on Sunday, Washington's "pivot" to the region is becoming more visible. It includes deployment of American Marines in Darwin, Australia, stepped up U.S. naval visits to the Philippines and many more joint drills with that nation's armed forces, as well as the lifting of a ban on lethal weapons sales to Vietnam.
But just as Washington seeks to expand American interests in Asia as a counterpoint to China's growing influence, some U.S. partners have shown less willingness to challenge Beijing. That may mean China will have a freer hand to assert its authority in the resource-rich South China Sea, where its territorial claims overlap those of Taiwan and four Southeast Asian countries.
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The drubbing Obama's Democrats took in this week's mid-term elections, defeats that were blamed by many on his leadership, will hardly strengthen his position in discussions with China or with allies in the region. Obama will have less room for maneuver on foreign policy now he has a Republican-controlled Senate to deal with, and the political focus in Washington is already starting to turn to the 2016 presidential election.
Although several countries, notably the Philippines and Vietnam, have sought closer U.S. ties as a defense against what they see as China's aggression in pursuit of its claims in the South China Sea, other long-established alliances have become less robust.
Beijing's increasing economic influence is a major reason. Southeast Asia's trade with China is up four-fold over the past decade to $350 billion last year and is forecast to reach $1 trillion by 2020.
Indonesia, traditionally a leading voice and strong U.S. ally in Southeast Asia, has signaled a foreign policy shift away from international activism following this year's election of a populist President Joko Widodo, who said in his election campaign that his focus would be on domestic affairs.
Rizal Sukma, a foreign policy adviser to Widodo, told Reuters there would be a shift in priorities from high-profile diplomacy, though Indonesia would continue to play a role in the South China Sea and support freedom of navigation and trade.
On the South China Sea, Widodo is unlikely to act without a crisis, said Greg Fealy, an Indonesia expert at the Australian National University. "The U.S. may well find it much more difficult to get any leverage," he said.
In Thailand, a military coup in May has shaken up its relationship with the United States. Since the coup, Washington has scaled back diplomatic contacts and reduced joint military exercises.
And Malaysia, next year's chair of the 10-nation Association of Southeast Asian Nations, has seen a wave of Chinese trade and investment and is working with Beijing on upgrading an ASEAN-China free-trade agreement.
"I think there is every reason to be concerned," over whether ASEAN will stand up to China, said Joseph Liow, a Southeast Asia expert at Washington's Brookings Institution think tank.
During his trip, Obama will attend the Nov. 10-11 Asia Pacific Economic Cooperation forum in Beijing and the Nov. 13 East Asia Summit in Myanmar. Perhaps most importantly, he will hold talks with Chinese President Xi Jinping on Nov. 11-12.
U.S. officials say he plans to press Xi about China's aggressive behavior in pursuit of maritime claims in Asia. "We are going to have to speak very directly and candidly about some of our concerns and our areas of disagreement," a senior U.S. administration official told Reuters.
Washington has had its recent successes in the region.
In April, the U.S. and the Philippines signed a new 10-year security pact allowing for a larger U.S. military presence.
In July, another U.S. ally, Japan, revised its interpretation of a pacifist postwar constitution to allow Japanese troops to assist a friendly state under attack.
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And Washington has also agreed to boost defense ties with Australia and agreed with India to negotiate a 10-year extension of a bilateral military cooperation deal.
Perhaps most eye-catching of all, nearly 40 years after the end of the Vietnam War, the United States last month partially lifted a long-time ban on lethal weapon sales to Vietnam to help Hanoi improve maritime security.
That followed tensions between China and Vietnam that flared in May after China's state-run CNOOC oil company parked a deepwater rig off Vietnam's coast in what Hanoi said was its exclusive economic zone, sparking the worst breakdown in ties between the two since a border war in 1979.
Joint U.S.-Philippine drills and exercises have more than quadrupled in the past two years, the Philippine military said. Its Subic Bay port saw 100 U.S. naval ship visits in the first 10 months of this year, up from 54 in 2011.
The Pentagon says it now has 1,150 Marines in Darwin, in northern Australia, up from an initial 200 in April 2012. It plans to lift that force to 2,500 in two years, pending an agreement with the Australian government.
A vital component of Obama's rebalance - a 12-country Trans-Pacific Partnership trade pact - has yet to be concluded. Obama has said he wants to see TPP progress as a result of his trip, but U.S. officials say they do not expect a deal given major outstanding issues. China is not one of those negotiating the TPP, but is open to joining one day.
"There's no country in the region, given China's rise ... who isn't essentially a strong supporter of America remaining strategically engaged in the region," said Russell Trood, an adjunct professor of U.S. studies at the University of Sydney.
"And yet when you ask them to stand up and nail their colors to the masthead, as it were, few are prepared to do it to the degree to which Washington would no doubt be reassured."