WASHINGTON — President Trump, following days of bellicose threats toward North Korea and jitters about a looming trade war with China, moved on several fronts Monday to ease tensions in East Asia, after making the region a flash point for his administration.

As he opened a long-awaited trade action against China, Mr. Trump used uncharacteristically restrained language and a multistep bureaucratic process that will likely put off punitive steps against Beijing for months, if not forever. On North Korea, several of the president’s top advisers tried to tamp down fears of a clash after his threat to rain “fire and fury” on the regime there.

In Seoul, Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, assured President Moon Jae-in of South Korea that military options against North Korea were a last resort. His message was the latest effort to reinforce a sense of calm that was earlier telegraphed by Defense Secretary Jim Mattis and Secretary of State Rex W. Tillerson.

Taken together, the administration’s tempered words underscored the complex reality that Mr. Trump faces in Asia: Having explicitly linked China’s cooperation on North Korea with his trade policy toward Beijing, the president is now softening his tough trade rhetoric to enlist China’s support in combating a nuclear threat from Pyongyang.