The question: Will it be enough?
Nearly seven months after he cancelled an Asian tour due to the U.S. government shutdown, Obama's failure to prevent Russia from annexing Crimea has sharpened concerns that America lacks the will or wherewithal to follow through on its much-touted “pivot'' to the Asia-Pacific.
"Words come easy,'' said Philippine political analyst Ramon Casiple. "But U.S. allies would want to know what help they can get when things reach a point of no return.''
The United States has been stepping up regional military deployments, but has made less progress on rebalancing through broader diplomatic and economic initiatives, such as the Trans-Pacific Partnership, a Pacific Rim free trade agreement.
Obama arrives in Tokyo on Wednesday for the first state visit to America's closest ally in Asia by a U.S. president since Bill and Hillary Clinton came in 1996. He will be the first sitting U.S. president to visit Malaysia since Lyndon Johnson in 1966. Allies South Korea and the Philippines, the two other stops on his agenda, are also keen to shore up security ties.
U.S. allies wonder if America has adequate capability to back them up in territorial rifts with China, Caspile says, given Washington's budget problems and preoccupation with crises elsewhere.
"The American objective is to reassure countries that America is here to stay and is going to keep a strong interest in dealing with China together with those countries,'' said Koichi Nakano, a political science professor at Tokyo's Sophia University.
A report released last week by the U.S. Senate Foreign Relations Committee urged that more effort and money be devoted to upgrading alliances in the Asia-Pacific. "A successful rebalance must underscore the strategic message that the policy represents an enduring U.S. commitment to the region, assuring our partners that we are in it for the long haul,'' it said.
Striving to allay Japan's worries over its territorial dispute with China and missile launches by North Korea, during a recent Asian tour U.S. Defense Secretary Chuck Hagel pledged two more ballistic missile defense destroyers for Japan by 2017. In a further show of solidarity, Hagel rebuked Beijing for escalating its territorial dispute with Tokyo over Japanese-controlled islands in the East China Sea that Japan calls the Senkaku islands and China calls the Diaoyu islands.
The U.S. is obligated to protect Japan from attack, but has sought to avoid taking a stand on sovereignty over the islands. Tokyo is hoping for more in the way of confidence building, says Hitoshi Tanaka, chairman of the Institute for International Strategy in Tokyo.
"We would like to see the president make a strong, clear statement about the Senkaku,'' said Tanaka. "There is a need for Japan and the U.S. to work to improve the security situation in East Asia.''
Obama's two-night stay in Tokyo _ just enough for the state visit the Japanese had pushed for, in itself sends a good message, said Matake Kamiya, a professor at the National Defense Academy in Yokosuka, near Tokyo.
"It's important not only for the psychology of the Japanese but also for the impression given to the Chinese and North Koreans,'' he said.
The U.S. has 50,000 troops in Japan and about 28,500 deployed in South Korea, where it just concluded joint U.S.-South Korean exercises. But Tokyo and Seoul remain at odds over a separate territorial dispute and lingering Korean resentment of Japanese aggression before and during World War II.
Getting an early start on fence-mending, Obama brought Japanese Prime Minister Shinzo Abe and South Korean President Park Geun-hye together for their first face-to-face meeting since they both took office over a year ago, on the sidelines of a recent nuclear security summit in The Hague.
A visit by Abe in December to Tokyo's Yasukuni Shrine, which enshrines 14 convicted war criminals among 2.5 million war dead, irked the U.S. and angered both South Korea and China.
At least two members of Abe's Cabinet, and dozens of other lawmakers, paid respects at the shrine just days before Obama's arrival in visits the South Korean side described as “deplorable.'' But the leaders' attention may well be diverted by a tragic ferry sinking, which left more than 300 missing or dead, most of them teenagers.
The United States already has a free-trade agreement with South Korea, which is likely to eventually join the Trans-Pacific Partnership. Both the U.S. and Japan had hoped to announce "substantial progress'' on the pact by the time of Obama's visit despite conflicts over tariffs on farm products and automobiles. Officials signaled Tuesday that a breakthrough was unlikely.
A TPP deal with Japan is vital for making headway with the other 10 countries in the trade bloc, which includes Malaysia, the third stop on Obama's swing through Asia, the market for about 60 percent of U.S. exports.
"Obama has two main agendas on this trip, which are to reaffirm the U.S. `pivot' policy on Asia and to close the final hurdles for the Trans-Pacific Partnership agreement,'' said James Chin, a political analyst with Monash University in Malaysia.
As the U.S. shifts more of its military assets into the Pacific region under new defense guidelines, it is stepping up cooperation with many Southeast Asian nations, including Malaysia.
Though Kuala Lumpur's treatment of opposition politicians is complicating matters, Washington wants improved ties with Malaysia, whose majority Muslims adhere to a moderate form of Islam. The U.S. has taken a leading role in the Indian Ocean hunt for the Malaysia Airlines jet that vanished on March 8 with 239 people on board.
Chinese naval exercises near the James Shoal, just 80 kilometers (50 miles) off the coast of Malaysia's Sarawak state, have strained Malaysia's resolve to avoid confrontation over territorial disputes.
Both the U.S. and Japan have stepped up support for the Philippines, the last stop on Obama's eight-day journey, with Tokyo offering retired coast guard cutters to help fend off intrusions by Chinese naval vessels near still other disputed islands in the South China Sea.
The Philippines is negotiating with Washington for a beefed up security agreement to allow more access for U.S. troops, ships and aircraft to detect and deter such incursions.
U.S. bases in the Philippines closed when the country ended their leases in 1992, though the two sides have an agreement allowing limited U.S. troop visits, mainly in the south where Filipino troops are battling militants.