With North Korea's drive to field a nuclear-armed missile rapidly emerging as President Donald Trump's first foreign crisis, his top diplomat is heading to a nervous region.
US Secretary of State Rex Tillerson, a former oil executive with no government experience, has yet to make an impact in Washington, where he has not even appointed a senior staff.
But this week he will head as emissary of the world's top power to Tokyo, Seoul and Beijing to tackle a nuclear stand-off that threatens to tip into a catastrophic war.
Tillerson will arrive in Tokyo on Wednesday for talks with Prime Minister Shinzo Abe and Foreign Minister Fumio Kishida, who watched Pyongyang's latest missile tests with alarm.
On Friday, he will be in Seoul and a South Korea mired in a domestic political crisis but also still braced for further provocations from its belligerent northern neighbor.
The secretary will meet Hwang Kyo-Ahn -- who is acting president until an election can be held to replace impeached leader Park Geun-Hye -- and talk with Foreign Minister Yun Byung-Se.
Then, on Saturday, Tillerson will be in China, the United States' nearest peer as a world power and perhaps the only one that retains any leverage over Kim Jong-Un's regime.
- Pressure -
China supported previous UN sanctions against North Korea, and has in theory halted coal imports from its smaller neighbor, but it is reluctant to take steps that could see the regime fall.
Since coming to office in January, and especially since the most recent North Korean missile tests last week, Trump has been looking for ways to turn up the pressure on Pyongyang.
"I think it's well known that we are looking currently at approaches to the North Korea question and there is a range of things that are being considered," a senior US official said.
Among the other options pushed by the hawkish wing of the Washington foreign policy community are secondary sanctions that would target any Chinese banks that work with Pyongyang.
But officials preparing the trip, briefing reporters anonymously at a time when most senior diplomatic positions in Washington are unfilled, said no major announcements are imminent.
"We're trying to come up with what the approach of the new administration is going to be," one said.
No peace treaty was signed after the 1950-53 Korean war, so Seoul and its US ally are technically still in a state of hostilities with its neighbor across a demilitarized zone.
Since the peninsula split, South Korea has become an economic power with democratic institutions, but there are still more than 28,000 US personnel deployed to aid in its defense.
Kim, the third leader in a dynasty that rules through oppression and a personality cult, has proved just as determined as his father and grandfather to develop a nuclear weapon.
North Korea has a small number of bombs and now it is testing an intercontinental ballistic missile and shorter-range rockets that could threaten US bases and cities in the Pacific rim.
- Secondary sanctions -
Most observers see China as the only power with the leverage to get its isolated neighbor to stand down, and existing United Nations-backed sanctions have had little effect so far.
The crisis is shaping up to be the key early challenge of Trump's presidency and the Pentagon has already provoked China's ire by deploying the THAAD anti-missile system in South Korea.
US officials insist THAAD is a purely defensive system designed to protect South Korea and Japan from Kim's missiles, but Beijing sees it as a threat to its own deterrent ability.
And the signals coming out of China are not encouraging for those in Washington who cling to the hope that Beijing may be ready to rein in its small but combative neighbor.
On Wednesday, Foreign Minister Wang Yi implied that the United States and North Korea were equally at fault for provoking the latest crisis and headed towards a "head-on collision."
Wang urged the US military to halt planned exercises with South Korea, in exchange for Pyongyang halting its nuclear and missile programs -- an idea Washington promptly dismissed.