Japan plans to dispatch its largest warship on a three-month tour through the South China Sea beginning in May, three sources said, in its biggest show of naval force in the region since World War II.

China claims almost all the disputed waters and its growing military presence has fueled concern in Japan and the West, with the United States holding regular air and naval patrols to ensure freedom of navigation.

The Izumo helicopter carrier, commissioned two years ago, will make stops in Singapore, the Philippines, Indonesia and Sri Lanka before joining the Malabar joint naval exercise with Indian and U.S. naval vessels in the Indian Ocean in July.

It will return to Japan in August, the sources said.

“The aim is to test the capability of the Izumo by sending it out on an extended mission,” one of the sources said.

“It will train with the U.S. Navy in the South China Sea,” he added, asking not to be identified because he is not authorized to talk to the media.

A Maritime Self-Defense Force spokesman declined to comment.

Taiwan, Malaysia, Vietnam, the Philippines and Brunei also claim parts of the maritime area, which has rich fishing grounds, oil and gas deposits and through which around $5 trillion of global sea-borne trade passes each year.

Japan does not have any claim to the waters but has a separate dispute with China in the East China Sea.

Japan wants to invite Philippine President Rodrigo Duterte, who has pushed ties with China in recent months as he has criticized the old alliance with the United States, to visit the Izumo when it makes a port call in Subic Bay, about 100 km west of Manila, another of the sources said.

Japan’s flag-flying operation comes as the United States under President Donald Trump appears to be taking a tougher line with China. Washington has criticized China’s construction of man-made islands and a buildup of military facilities that it worries could be used to restrict free movement.

Beijing in January said it had “irrefutable” sovereignty over the disputed islands after the White House vowed to defend “international territories.”

The 249-meter-long Izumo is as large as Japan’s World War II-era carriers and can operate up to nine helicopters. It resembles the amphibious assault carriers used by the U.S. military but lacks their well deck for launching landing craft and other vessels.

Japan in recent years, particularly under Prime Minister Shinzo Abe, has been stretching the limits of the pacifist Constitution. The government has designated the Izumo as a destroyer because the Constitution forbids the acquisition of offensive weapons. The vessel, nonetheless, allows Japan to project military power well beyond its territory.

Based in Yokosuka, Kanagawa Prefecture, which is also home to the U.S. aircraft carrier Ronald Reagan, the Izumo’s primary mission is anti-submarine warfare.