SEOUL, South Korea — A week ago, things could not be going better for President Moon Jae-in of South Korea. He was successfully arranging a meeting between North Korea’s leader, Kim Jong-un, and President Trump. His approval ratings at home were soaring. The tone had changed so much that Mr. Trump had even called Mr. Kim “very honorable.”
Now, the matchmaking role that has defined Mr. Moon’s presidency is suddenly in doubt.
After months of unusual bonhomie, North Korea on Wednesday withdrew from talks with South Korea and threatened to cancel the planned June 12 summit meeting between Mr. Kim and Mr. Trump, which Mr. Moon’s aides have spent months trying to set up.
For Mr. Moon, the North’s reversal brought home the difficulties in playing matchmaker between his country’s most fearsome foe and its most important ally, both countries run by an impulsive and often unpredictable leader.
It shows the extraordinarily difficult challenge that Mr. Moon confronts. He faces skepticism from both Pyongyang and Washington that he can be an honest broker. North Korea still considers South Korea an American stooge. In the United States, conservatives who have the president’s ear worry that progressive South Korean leaders like Mr. Moon will ease sanctions, breaking ranks with Washington in their eagerness to reconcile with the North.
“A matchmaker can succeed when boy and girl like each other,” said Moon Seong-mook, a senior analyst at the Korea Research Institute for National Strategy in Seoul. “But the United States and North Korea have very different ideas on how to achieve denuclearization.”
It remains unclear whether the North’s sudden shift in attitude signaled a return to brinkmanship or mere posturing before the summit meeting, which is slated to take place in Singapore.
While most South Koreans support Mr. Moon’s intermediary role, North Korea’s actions on Wednesday give political ammunition to his conservative enemies, who call him a naïve amateur who has fallen for Pyongyang’s trap of “false peace.” They fear that Mr. Moon will not denuclearize the North, but will weaken Seoul’s alliance with Washington.
North Korea’s reversal has already dampened some of the optimism that pervaded South Korea after Mr. Moon’s dramatic meeting with Mr. Kim on the inter-Korean border on April 27. His party had been hoping to benefit politically from the Singapore meeting, which would take place a day before elections of mayors and provincial governors in South Korea. Mr. Moon’s North Korea diplomacy has loomed large over