TOKYO- Prime Minister Shinzo Abe will visit the Philippines, Australia, Indonesia and Vietnam on a six-day trip from Thursday aimed at strengthening security cooperation amid China's rising maritime assertiveness.

Abe's Asia-Pacific tour also comes as uncertainties loom over the commitment of the incoming U.S. administration to the region following the inauguration Jan. 20 of U.S. President-elect Donald Trump, who has suggested he will shift to a protectionist trade policy.

"The trips are aimed at reaffirming the importance of the U.S. alliance network in the Asia-Pacific region and strengthening coordination with major countries in the region," a senior Japanese official said.

"Japan hopes to fulfill a leading role in promoting close coordination with Asia-Pacific nations at a time when uncertainties are increasing in the political, security and economic fields," the official said.

The Philippines and Australia are allies of the United States, while Indonesia is a leading member of the 10-member Association of Southeast Asian Nations. Vietnam, also an ASEAN member, is this year's chair of the Asia-Pacific Economic Cooperation forum, which gathers Pacific Rim economies including the United States.

During the trip, Abe is likely to highlight the importance of multilateral free trade pacts. Trade partners are now watching whether Trump will pull the United States out of the Trans-Pacific Partnership free trade agreement, reached with Japan and 10 other countries, as he has pledged.

The TPP has been led by outgoing President Barack Obama as a major component of his policy of pushing a strategic rebalancing to the Asia-Pacific region.

Abe hopes to share with the four nations concerns about China's military buildup and assertiveness in disputed waters of the South China Sea, renewed when China's sole aircraft carrier sailed into the western Pacific for the first time last month, according to Japanese officials.

Abe's first stopover will be the Philippines on Thursday for talks with President Rodrigo Duterte, who took office June last year. Abe is expected to underscore Japan's cooperation with the Philippines in economic development, the fight against terrorism and infrastructure building among other issues.

Japan will also promise its support as Manila chairs a series of ASEAN meetings this year, where the South China Sea issue is likely to be high on the agenda.

Japan is not a claimant in the South China Sea disputes between China and five other governments, including the Philippines and Vietnam, but it is concerned about China's rising military presence in the resource-rich area which is also a busy shipping lane.

Tokyo also faces challenges from Beijing related to China's claim to the Japanese-controlled Senkaku Islands in the neighboring East China Sea.

On Saturday, Abe will meet Australian Prime Minister Malcolm Turnbull with the aim of affirming the need for strong security coordination and cooperation between Japan, Australia and the United States to maintain a rule-based international order, the officials said.

On Sunday, Abe will travel to Indonesia, where he is expected to confirm with Indonesian President Joko Widodo cooperation in maritime security and economic development in the fast-growing Southeast Asian nation.

While Indonesia is also not a claimant in the disputes in the South China Sea, where China has been conducting massive land reclamation projects, infrastructure development, seismic surveys and fishing activities, encounters between Indonesian and Chinese vessels have highlighted a clash of interest between the two countries.

In Vietnam, Abe will meet Prime Minister Nguyen Xuan Phuc, President Tran Dai Quang and other top officials to strengthen the bilateral relationship.

Abe is likely to offer patrol vessels to help Vietnam strengthen its maritime patrol capabilities amid China's rising maritime assertiveness, the officials said.

The premier will return to Japan on Jan. 17. (Kyodo News)