The Pacific Vanguard exercise near the U.S. island of Guam takes place ahead of President Donald Trump's visit to Japan this weekend, as Washington looks to allies in Asia to help counter China's military might in the region.

"Pacific Vanguard joins forces from four, like-minded maritime nations that provide security throughout the Indo-Pacific based on shared values and common interests," Vice Admiral Phillip Sawyer, commander of the U.S. Navy's Seventh Fleet, said in a statement.

The six-day exercise involves two Japanese destroyers, two Australian frigates and a destroyer from South Korea, with as many as 3,000 sailors participating.

The U.S. Navy has deployed five ships as well as fighter jets and maritime patrol planes for the drills, which include live fire and anti-submarine warfare exercises.

Pacific Vanguard is the latest show of combined naval force in the Asia Pacific region.

This month U.S. ships conducted drills with French, Japanese and Australian ships in the Bay of Bengal, and held separate exercises with a Japanese helicopter carrier and warships from India and the Philippines in the disputed South China Sea.

China claims almost all of the strategic South China Sea, through which passes about a third of global seaborne trade. Brunei, Indonesia, Malaysia, the Philippines and Taiwan have competing claims to the waterway. Vietnam calls the waters the East Sea and has consistently asserted its sovereignty rights over the area.

On Wednesday, the U.S. Navy sent two ships through the Taiwan Strait, its latest transit through the sensitive waterway and a move likely to anger Beijing at a time of tense relations between the world's two biggest economies.

Taiwan is one of a growing number of flashpoints in the U.S.-China relationship, which also include a bitter trade war, U.S. sanctions and China's increasingly muscular military posture in the South China Sea, where the United States also conducts freedom-of-navigation patrols.