Park Geun-hye, who was ousted as South Korea’s president Friday, salutes during her inauguration on Feb. 25, 2013, at the National Assembly in Seoul. (Lee Jin-man/Associated Press)

After the historic ouster of President Park Geun-hye on Friday, scandal-weary South Koreans began turning their attention to a new election due within 60 days — and to the prospect that her successor could try to reset relations with neighboring North Korea and its powerful patron, China.

In the three months since Park was suspended over corruption allegations, plunging the country into limbo amid protracted impeachment proceedings, the regime in North Korea has launched five ballistic missiles and a volley of threats, and is accused of ordering the assassination of the leader’s half brother.

Add to that China’s anger over the deployment of a U.S. missile defense system to South Korea and uncertainty about President Trump’s administration in Washington, and the lack of leadership in South Korea could hardly have come at a more sensitive time.

[ China’s anger over U.S. antimissile system poses challenge to Trump ]

A protester wearing electric lights attends a rally in Seoul calling for impeached President Park Geun-hye’s arrest on Friday. (Ahn Young-joon/Associated Press)

“A political vacuum like this in a key ally that borders a major nuclear threat is not good for the U.S.,” said John Delury, an American political scientist in Seoul. “I think it’s been underestimated as a danger and as a destabilizing factor.”

Secretary of State Rex Tillerson will encounter this problem firsthand when he arrives in Seoul next week for discussions about North Korea with a South Korean counterpart who is on his way out. Tillerson will also hear about the rise of a progressive candidate whose approach toward China and North Korea could differ sharply from that of the impeached president — and from the stance of the United States.

The Trump administration is conducting a policy review to decide how to deal with North Korea’s threats, and there is plenty of talk in Washington about “kinetic options” — a euphemism for some kind of military action. Meanwhile, in Tokyo, some ruling-party lawmakers are openly pushing for Japan to develop the capacity to preemptively strike North Korea.

That is the kind of talk that South Korea should be shutting down, Delury said. In addition to its nuclear and missile programs, North Korea has conventional artillery lined up along the demilitarized zone and aimed at Seoul, a metropolis of 25 million people.

“The role of a South Korean president, whether liberal or conservative, is to be the person who gently takes that option off the table,” Delury said, referring to a preemptive strike. “The South Korean president has to be saying, ‘If you take out their missile pad, they take out our capital.’ But that hasn’t been happening.”

Park was immediately dismissed from office Friday after South Korea’s Constitutional Court upheld a legislative impeachment motion, ruling unanimously that she had “continuously” broken the law.

[Presidential scandal shows that ‘Korean disease’ of corruption is far from cured]

(Jason Aldag,Anna Fifield,Gillian Brockell/The Washington Post)

Elections will be held in early May, and the latest opinion polls show Moon Jae-in, a progressive who unsuccessfully challenged Park for the presidency in 2012, holding a strong lead.

Moon favors the “sunshine policy” of engagement with North Korea — the liberal idea from the late 1990s that engagement can help open up the closed state and narrow the gap between the two Koreas.

This sunshine policy ended in 2008 with the election of a conservative president who took a tough approach toward North Korea, a stance maintained by Park.

Following North Korea’s nuclear test at the beginning of last year, Park’s government closed the inter-Korean industrial complex that was the linchpin of the sunshine policy, accusing the North of using South Korean cash from economic engagement projects to bankroll its weapons programs.

Moon, however, has said he would like to resume engagement with North Korea and would go to Pyongyang for talks with its leader.

“If Moon wins the general election, he will emphasize South Korea’s alliance with the U.S. and a strong defense posture,” said Lee Chung-min, a professor of international relations at Yonsei University. “But his heart will lie in fostering deeper engagement with the North and negotiating an early summit with Kim Jong Un.”

Moon has also signaled an openness to reviewing the Park government’s agreement to host the United States’ Terminal High Altitude Area Defense (THAAD) antimissile battery.

[ U.S. military deploys advanced defensive missile system to South Korea, citing North Korean threat ]

The agreement was reached last year to protect against North Korean missiles, and the system was due to arrive in South Korea this summer. But in a surprise announcement, the Pentagon said the first shipment arrived in South Korea on Monday.

This has sparked widespread speculation in South Korea that the United States expected Park to be impeached and wanted to make the deployment more difficult to reverse. The U.S. military command in South Korea said the deployment was being carried out according to schedule.

China has vehemently objected to the arrival of THAAD in the region, viewing the deployment as a U.S. attempt to keep China, not just North Korea, in check. To prod Seoul to change its mind, Beijing has imposed painful restrictions on South Korean imports ranging from toilet seats to pop music.

“We are all very clear that the crux of the problem between China and South Korea is that South Korea is ignoring China’s concerns and is deploying the THAAD antimissile system with the United States,” Chinese Foreign Ministry spokesman Geng Shuang said Friday.

“We once again urge South Korea to focus on the interests of the Chinese and Korean people,” he said.

But analysts say that even if the progressive Moon becomes South Korea’s next president, he will face difficulties in backtracking on THAAD or returning to the sunshine policy.

“While China might expect a U-turn over THAAD if Moon becomes president, it will be extremely difficult for Moon to do that, since THAAD is being placed primarily for the defense of the United States forces in Korea,” said Lee, the Yonsei professor.

Trump could seek to dissuade Moon by making South Korea pay more for its defense costs and speeding up efforts to renegotiate the Korea-U.S. free-trade agreement. “Despite Moon’s inclination to oppose THAAD deployment, he will not undo it at the expense of worsening ties with Trump just as Moon begins his term in office,” Lee said.

Likewise, it would be difficult to go back to the kind of sunshine policy of previous liberal presidents, said Robert Kelly of Pusan National University. “I don’t think there is much support for major engagement any more,” he said.

This is partly because public opinion has changed dramatically, thanks to two North Korean attacks in 2010 that left more than 50 South Koreans dead, as well as the Park government’s assertion that engagement money was funding weapons development.

“I think Moon would have to fight hard to get that kind of engagement off the ground — he’d be pushing against the Americans and against his own people,” Kelly said.

But for South Koreans who wanted Park out, there is a sense of opportunity.

“Today is just the beginning,” said Kim Kyoung, a housewife who attended every rally against the impeached president and returned to central Seoul on Friday night to celebrate Park’s departure. “South Korea developed very quickly, but now we have an opportunity to move slowly and help our democracy mature.”

Congcong Zhang in Beijing contributed to this report.

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Today’s coverage from Post correspondents around the world

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