TOKYO -- A lot has happened in Asia while the United States was off fighting its wars in Iraq and Afghanistan, and most of it can be summed up in one word -- China. Fueled by China's amazing growth and the promise of its huge and expanding consumer market, the Asia-Pacific region is now, as experts like to say, the global economy's center of gravity. Sorry, Europe.
But prosperity requires stability.
As President Barack Obama tours the region to push his year-old pivot to the Pacific policy, the big question on everybody's mind is how much of a role Washington, with its mighty military and immense diplomatic clout, can play in keeping the Pacific - well, pacific. Here's a look at how different countries perceive the U.S. Pacific policy and how it impacts them:
CHINA: HOW NOT TO TRAIN YOUR DRAGON
As far as Beijing is concerned, Obama's pivot was pulled right out of the old Cold War containment playbook. Afraid of China's rise, Beijing believes, Washington is trying to enflame new tensions by isolating it and emboldening the countries that China has territorial disputes with, which is just about everybody with whom it shares a border.
"Using China's rise and the `China threat' theory, the U.S. wants to convince China's neighbors that the Asia-Pacific needs Washington's presence and protection in order to `unite' them to strike a `strategic rebalance' against China in the region," security scholar Wang Yusheng wrote recently in the China Daily.
It's a strategy that's bound to lose, Beijing says.
China sees its rise as inevitable and unstoppable and believes its neighbors will ultimately opt for stronger ties while gradually excluding the U.S. Beijing also views its economic dominance as an unalloyed good. And as it tests out its first aircraft carrier, stealth jets, cyber capabilities and high-tech missiles, it is in an increasingly strong position to deny Washington access to its shores and some key Pacific sea lanes, which could be a problem if Obama's pivot ever has to go from push to shove.
JAPAN: ALREADY FEELING THE PINCH
Without a doubt, Japan is Washington's most faithful security partner in the Pacific. And it's the most pinched by China's rise.
For months, Japan and China have been in an increasingly tense dispute over a group of small, uninhabited islands in the East China Sea. The near-constant presence of Chinese ships around them has stretched the Japanese Coast Guard to its limits. Japan's air force says Chinese surveillance flights in the area have increased significantly.
Wary of getting caught up in the volatile brew of nationalism, historical animosity and populist politics that is fueling the flare-up, the U.S. has been careful not to take sides. Instead, it has urged the two countries to work out their problems among themselves, diplomatically.
That has confounded many in Japan, which hosts 52,000 U.S. troops under a treaty signed in 1960 that obliges the U.S. to defend territories under Japanese administration. Washington has repeatedly affirmed that includes the isles at the center of the current tensions with China. Tokyo would have preferred at least some moral support to its claim.
"It's strange," said Kazuhiko Togo, a former senior diplomat who now heads the Institute for World Affairs at Kyoto Sangyo University. "I trust the U.S. as our ally, but we need to address this issue of U.S. `neutrality.' "
MEANWHILE, IN THE SOUTH CHINA SEA ...
Washington took a similarly standoffish stance early this year in the dispute between China, Brunei, Malaysia, the Philippines, Vietnam and Taiwan over the South China Sea islands, believed to be rich in gas and oil and straddling busy shipping routes.
The Philippines - America's closest ally in that dispute - eventually pulled its ships out of the hotly contested Scarborough Shoal, but Chinese vessels have remained.
Manila-based political analyst Ramon Casiple said the disputes have left America's allies more aware of their own vulnerabilities and what they can - or can't - expect from the U.S.
"America's treading a very fine line," Casiple said. "It has to reassure its allies that at the end of the day the U.S. would be there for them." He added that the U.S. has made it clear it is not willing to risk a major confrontation in which its options would be limited "to either intervene or lose influence."
There is, however, one other thing it might do in the meantime.
When U.S. Defense Secretary Leon Panetta visited Vietnam in June, he hinted the Navy would like access to Cam Ranh, a deep water port facing the contested waters of the South China Sea. Hanoi's counter-proposal?
Lift a ban on selling it lethal weapons.
TAIWAN: LEFT OUT IN THE COLD
Best friends forever? Not so much.
As China has gotten stronger and more important to the U.S. economy, Washington has become extremely wary of engaging Taiwan as a full security partner - a big pullback from the 1950s and the 1960s, when the two had a formal defense treaty and the U.S. based thousands of troops on what it considered a -- if not the -- key forward base to keep China at bay.
Today, cooperation is limited to some intelligence sharing, the training of Taiwanese air force personnel in the U.S., occasional security consultations and very restricted arms sales -- definitely not the kind of advanced F-16 fighters and diesel submarines the Taiwanese military really wants.
Even so, political scientist Alexander Huang of Taipei's Tamkang University says Taiwan can play a role in Obama's pivot - but only if Washington decides to make a clear commitment.
THE KOREAS: STEALTH OVER SEOUL?
Ah, North Korea.
It's got a new leader, about whom, typically, the world knows almost nothing, a nuclear weapons/ballistic missile program that it likes to trot out every so often to raise regional tensions and a belligerent attitude toward the U.S.
But Obama has a friend in Seoul.
Back in the 1950s, the U.S. fought on Seoul's side in the Korean War - and contemplated nuking China before it was over. China still supports the North, and Washington continues to have about 28,500 troops in the South. South Korea also buys about 70 percent of its weapons from the United States, and a big payday for an American company might come soon after Obama's inauguration, when South Korea is expected to formally announce the winner in a $7.6 billion project to build 60 sophisticated fighter jets.
The deal will be South Korea's biggest-ever weapons procurement. The top contender is believed to be Lockheed Martin's stealthy F-35 Joint Strike Fighter - which after a long run of development problems and cost overruns could certainly use a multi-billion dollar boost. Boeing and European aerospace giant EADS are also in the running.
AUSTRALIA: LIVING WITH THE U.S. MARINES
Australia got one of the first waves from the pivot when the U.S. announced last year it would begin rotating up to 2,500 U.S. Marines through the northern city of Darwin. Now the U.S. is seeking access to an Australian navy base south of the western city of Perth and to bombing ranges in the northern Outback.
Some experts fear the relationship may be moving too fast.
On one hand there is broad support for Australia's defense relationship with the U.S., so having American Marines was seen as a natural step. But it has also raised concerns that Washington will push for more - something Australia might not be ready for. After all China is central to Australia's economy, buying a bulk of its mineral and coal resources.
"What worries us is the way in which it seems to confirm that the United States and China are increasingly viewing each other as strategic rivals," said Hugh White, professor of strategic studies at Australian National University.
"We worry about the idea of the U.S.-China relationship becoming more adversarial," he said. "America wants to remain the dominant power in Asia, and China wants to become the dominant power in Asia.
"What the rest of us all want is for neither of them to be the dominant power in Asia."
-- AP writers Christopher Bodeen in Beijing; Peter Enav in Taipei, Taiwan; Jim Gomez in Manila, Philippines; Hyung-jin Kim in Seoul, South Korea; Elaine Kurtenbach in Tokyo; Chris Brummitt in Hanoi, Vietnam; Jocelyn Gecker in Bangkok and Kristen Gelineau in Sydney contributed to this report.