Rex Tillerson

WASHINGTON — Secretary of State Rex Tillerson plunges this week into the increasingly volatile situation in North Asia with visits to Japan, South Korea and China, the region’s central players for dealing with North Korea’s missile launches and nuclear tests. Complicating the mission are Chinese concerns about how the U.S. has responded so far.

Beijing strenuously objects to the initial deployment to South Korea of a U.S. missile defense system. One of Tillerson’s chief tasks will be to assuage Asia’s biggest country and arrange a much-anticipated visit by Chinese President Xi Jinping to the U.S.

Tillerson’s four-day trip will be closely watched for signs of how the Trump administration will approach the escalating tensions with North Korea, whose leader has disregarded international appeals to disarm and accelerated weapons development. The North conducted two nuclear tests and 24 ballistic missile tests last year, deepening concern in Washington that it could soon develop a nuclear-tipped missile capable of reaching the U.S.

Last week, North Korea launched four missiles into the ocean off Japan as the U.S. and South Korea began annual drills. The allies call the drills routine. Pyongyang regards them as an invasion rehearsal.

The Trump administration is searching for new ideas to stop North Korea in ways that years of international sanctions and diplomatic isolation have failed to do.

While administration officials say all options are on the table, including military ones, early signs indicate the U.S. wants to ensure current sanctions are properly applied, targeting the government’s revenue sources and ability to import sensitive technology usable in nuclear weapons and missiles.

For now, there appears to be no desire to negotiate with North Korea — a holdover stance from the Obama administration, which demanded the North commit to denuclearization.