When Moon Jae In and Donald Trump met at the United Nations on Monday, South Korea’s president hailed his American counterpart for helping guide nuclear talks to a point where “North Korea’s decision to relinquish its nuclear program has been officialized to a degree that not even those within North Korea can reverse.”

“You are, indeed, the only person who can solve this problem,” Moon said of Trump, employing the kind of superlative language that Trump adores and that earned the American president guffaws during his address to the UN General Assembly on Tuesday. “Thanks to your bold decision and new approach, we are in the process of solving a problem that no one has been able to solve in the decades past.” The North Korean leader, Kim Jong Un, who just met with Moon in Pyongyang and may meet soon with Trump for a second summit, “repeatedly conveyed his unwavering trust and expectations for you,” Moon added.

But just a day after heaping on the praise, with Trump across town, South Korea’s leader amped up the pressure on the United States during an appearance at the Council on Foreign Relations in New York on Tuesday. Hours after describing Kim’s decision to denuclearize as irreversible, Moon characterized that denuclearization as contingent on the United States and other countries making corresponding concessions along the way.