Trump, South Korean President to focus on North Korea at first meeting

South Korean President Moon Jae-in and U.S. President Donald Trump are set to meet in Washington on Thursday for the first time, a highly anticipated summit that will serve as an early test of the new leaders' relationship following several differences over key policies.

The discussions between Messrs. Trump and Moon, who will have dinner Thursday night at the White House and meet again on Friday, come amid growing urgency about confronting the threat from North Korea. The two leaders have suggested dramatically different approaches to the issue.

Mr. Moon, South Korea's first left-leaning president in nearly a decade, has called for closer ties with North Korea, primarily through economic cooperation, while the Trump administration has called for tougher sanctions, military pressure and diplomatic isolation.

White House officials said North Korea is likely to dominate the talks between Messrs. Trump and Moon. They played down differences in the two leaders' approaches and said Mr. Trump will stress to Mr. Moon the need to coordinate their policies.

Mr. Trump's policy is to apply pressure on North Korea "to change their calculus to have substantive talks with us once they show they are willing to reduce the threat," a senior White House official said. The official said Mr. Trump sees nothing "problematic" with Mr. Moon's positions.

The U.S. administration is seeking to ramp up sanctions on North Korea and apply new diplomatic pressure to Pyongyang, though the White House official said no new sanctions are imminent.

"The State Department has been talking to our friends and partners throughout the world really to address North Korea's trade, to address many of their illegal activities sometimes conducted under the guise of diplomatic missions to raise capital, hard currency for their weapons programs," the official said. "I think there's plenty more pressure that could be brought to bear on North Korea in the form of U.N. Security Council resolutions and also unilateral sanctions by the United States."

The U.S. wants China to do more to cut off North Korea's economic pipeline. Mr. Trump, who said last week that North Korea is a threat that has to be "probably dealt with rapidly," recently wrote on Twitter that China's effort to use its influence on North Korea "has not worked out." The senior White House official echoed that view, saying "China is still falling short on what it could bring to bear on North Korea."

Mr. Trump will host Mr. Moon for cocktails and dinner Thursday night in the State Dining Room. The two will have an official meeting on Friday at the White House, followed by joint public statements.

Mr. Trump's comments about South Korea and U.S. relations, both as a candidate and since taking office in January, have roiled South Korea. Mr. Trump said in April that he wanted to renegotiate a trade deal with South Korea. He said South Korea should pay for a U.S. missile-defense installation known as a Terminal High-Altitude Area Defense system, or Thaad, that is designed to protect against a North Korean missile attack. Days later, Lt. Gen. H.R. McMaster, Mr. Trump's national-security chief, told his South Korean counterpart that the U.S. would pay for the system.

Mr. Trump also has suggested in the past that South Korea pay more for the cost of U.S. troops stationed in the country, a deployment that long has been a tenet of America's security alliance with the country.

The alliance particularly has been tested by the troubled deployment of Thaad. Over the past 12 months, Thaad has become a political football, upending ties between Seoul, Washington and Beijing, and even straining relations between Mr. Moon and his own defense ministry.

South Korean commentators and media have drawn comparisons with the two previous left-leaning South Korean presidents, whose summit meetings with then-President George W. Bush, a conservative, were widely regarded as failures.

Evan Medeiros, managing director for Asia at Eurasia Group, said that while a face-to-face meeting would help stabilize relations in the near term, it "will not solve underlying differences on missile defense, North Korea and economic ties. Disagreements on these issues are just below the surface."

Mr. Medeiros, who served on former President Barack Obama's National Security Council as senior director for Asian affairs, said, "Moon's ambiguous stance on Thaad, his weak commitment to increasing pressure on Pyongyang, and his penchant for engagement with the North will raise tensions with the U.S. later this year."

Kang Kyung-wha, South Korea's newly-appointed foreign minister, directly addressed concerns that Messrs. Trump and Moon don't see eye to eye. In her first policy address on Monday in Seoul, Ms. Kang said the two leader's North Korea policy was in sync and that the summit would "underscore their common vision and mutual understanding."

Ms. Kang also reaffirmed that Mr. Moon's decision to freeze Thaad deployment in South Korea didn't mean that Seoul would reverse Thaad or remove it altogether, in remarks aimed at soothing concerns in Washington about the alliance.

On the issue of the five-year-old U.S.-Korea Free Trade Agreement, known as Korus, the U.S.'s largest bilateral trade pact, Mr. Moon's aides expect Mr. Trump will be eager to discuss the issue. Mr. Trump has lambasted it as "a horrible deal."

And when Mr. Trump called Mr. Moon last month to congratulate the South Korean leader on his electoral victory, a major topic was Korus, said Choi Jong-kun, a professor at Yonsei University in Seoul and a campaign adviser to Mr. Moon on foreign policy.

"I think Mr. Trump is more eager to talk about the free-trade agreement than Thaad," Mr. Choi said.

On an interpersonal level, some analysts have expressed worries about the personal rapport and body language between Mr. Trump and Mr. Moon.

Mr. Moon is a careful, measured politician who doesn't speak English and is only believed to have visited the U.S. once. Mr. Trump's meetings with China's Xi Jinping and Japan's Shinzo Abe have been marked by personal warmth and lavish praise.

"Both Abe and Xi had the advantage that they're now very seasoned political figures," said Michael Mazarr, a senior political scientist at Rand Corp., a policy think tank. "Moon will still be in the process of accumulating that" experience.

"It's a meeting between two people who haven't met each other, so anything can happen," Mr. Choi said. "But the alliance is not just about the personal relationship, but about institutional consistency."

The senior White House official said it is possible at some point Messrs. Trump, Abe and Moon could jointly meet.

Write to Jonathan Cheng at jonathan.cheng@wsj.com and Carol E. Lee at carol.lee@wsj.com