TOKYO (Reuters) - U.S. Defense Secretary Jim Mattis on Saturday played down any need for major U.S. military moves in the South China Sea to contend with China’s assertive behavior, even as he sharply criticized Beijing for “shredding the trust of nations in the region.”

U.S. Defense Secretary Jim Mattis speaks at a joint news conference with Japan's Defense Minister Tomomi Inada after their meeting at the Defense Ministry in Tokyo, Japan, February 4, 2017. REUTERS/Toru Hanai

“At this time, we do not see any need for dramatic military moves at all,” Mattis told a news conference in Tokyo, stressing that the focus should be on diplomacy.

In his Senate confirmation hearing, Secretary of State Rex Tillerson said China should not be allowed access to islands it has built in the contested South China Sea. The White House also vowed to defend “international territories” in the strategic waterway.

But how the United States would achieve that has been unclear, including whether it would have a military dimension.

Analysts have said Tillerson’s remarks, like those from the White House, suggested the possibility of U.S. military action, or even a naval blockade.

Such action would risk an armed confrontation with China, an increasingly formidable nuclear-armed military power. It is also the world’s second-largest economy and the prime target of Trump accusations of stealing American jobs.

Mattis suggested that major military action was not being currently considered.

“What we have to do is exhaust all efforts, diplomatic efforts, to try to resolve this properly, maintaining open lines of communication,” Mattis said, in his most complete remarks on the issue to date.

“And certainly our military stance should be one that reinforces our diplomats in this regard. But there is no need right now at this time for military maneuvers or something like that, that would solve something that’s best solved by the diplomats.”

China claims most of the South China Sea, while Taiwan, Malaysia, Vietnam, the Philippines and Brunei claim parts of the waters that command strategic sea lanes and have rich fishing grounds along with oil and gas deposits.

Mattis criticized China’s actions.

“China has shredded the trust of nations in the region, apparently trying to have a veto authority over the diplomatic and security and economic conditions of neighboring states,” he said.