Secretary of State Rex Tillerson has arrived in Tokyo to begin a a six-day sweep through Northeast Asia. It's his first trip there as America's top diplomat, and he heads into a region full of challenges, both old and new.
In South Korea, where Tillerson is expected on Friday, the government is still sorting things out following last Friday's ouster of the country's president, Park Geun-hye. The historic impeachment on corruption charges brought on a power vacuum in Seoul — just as the new U.S. administration begins to engage with Asia.
"South Korea now enters a vortex of a political campaign, an election that has to take place in two months," says John Delury, a professor of international relations at Seoul's Yonsei University. He echoes recent Korean opinion polls in saying the government here is likely to shift to the more liberal opposition party when elections are held in early May.
Delury says that could bring significant change South Korea's policy regarding the North.
"Liberals think you engage North Korea," he says. "You draw them out. You have dialogue. You work on denuclearization but you have to work on a lot of other issues at the same time."
The North Korean threat is a top priority for Tillerson's trip. Since President Donald Trump took office, North Korea has twice tested missiles — last week firing four of them into the Sea of Japan. North Korea watchers say it appears to be preparing for another rules-breaking nuclear test. State's spokesman Mark Toner admits existing approaches to curb Pyongyang haven't worked.
"Thus far we have been unable to persuade them either through U.N. action, through sanctions, whatever. So I think we need to look at new possibilities," Toner said on Monday.
Those likely to take charge in South Korea aren't the leaders Tillerson will be meeting with this week. He'll instead talk through the North Korea threat and other regional issues with a lame duck South Korean government that was picked by a president who's no longer there.
"South Korea has two more months of a political vacuum," says Delury. "There's a lot of tensions.
"Just from a South Korean perspective, the relationship with China is quite bad, over THAAD [a missile defense system the U.S. is deploying in South Korea against Chinese objections], the relationship with Japan is bad, mostly over [World War II] history issues.
"And the relationship with the United States is uncertain, just because all of the questions around Trump."
China is the last leg of Tillerson's Asia trip, and the missile defense system promises to get a hearing, from various perspectives, on each stop, beginning with Japan tomorrow. The State Department says getting cooperation from China, Japan and South Korea is key to trying to slow down North Korea's advancing nuclear program.
"Everybody agrees on the challenge, which is how do you stop North Korea's bad behavior?" said Toner.
Not everyone agrees on how to solve it. And a key player in the region will soon change. Adding another complication to what was already one of the thorniest issues facing the White House.
NPR's Michele Kelemen contributed to this story.