It’s not immediately clear whether the Moon-Kim call took place. Regardless, the South Korean president is now in Washington, on a mission to first persuade Trump, not Kim, to consider a compromise between the big and small deals. After meeting with Trump, President Moon is likely to hold a fourth summit with Kim, or send envoys to Pyongyang, according to four South Korean officials.

The collapse of the February summit stunned South Korean officials, who had pinned all sorts of plans for reconciling with North Korea on a breakthrough in Hanoi. Seoul is now working on a rather unfortunately named “good enough” deal. But there’s no indication yet that Trump or Kim will accept it.

As South Korean officials describe it, the good-enough deal involves the United States and North Korea committing to a comprehensive agreement on peace, denuclearization, and new relations (a U.S.-style big deal) that will be implemented step-by-step (a series of North Korea–style small deals). The idea is to get North Korea to accept the end state, and the United States the process, that each dismissed in Hanoi. This good-enough deal would come in the form of a road map for reaching the desired goal within some specified time frame.

Read: How the White House is spinning the North Korea summit collapse

President Moon’s biggest potential obstacle in his meeting with Trump concerns economic sanctions against North Korea. U.S. officials such as Secretary of State Mike Pompeo and National Security Adviser John Bolton argue that maintaining sanctions is the key to compelling Kim to make a deal, while South Korean officials contend that easing sanctions could encourage the North Korean leader to strike an agreement. This is a fundamental philosophical difference that will have to be resolved for negotiations to progress.

The senior South Korean official who spoke about the Trump-Moon call suggested that Trump’s decision to walk away from the Vietnam summit was a response to political pressures back home to not strike a bad deal. The official noted that in Hanoi, the United States and North Korea had “strong agreement” on formally declaring an end to the Korean War, opening liaison offices in the other country’s capital, and providing North Korea with an economic-incentives package. U.S. negotiators, however, “crushed North Korea with their maximalist position” that Pyongyang completely give up not just nuclear weapons but also its biological and chemical weapons.

“A small deal is not a bad deal,” the senior South Korean official argued. If the Yongbyon complex were to be dismantled, North Korea would be eliminating its sole facility for producing plutonium and tritium for use in nuclear bombs, the official said. (The North has other suspected sites for producing highly enriched uranium and plenty of warheads and delivery systems for those bombs, which would all still exist if Yongbyon were destroyed. Experts disagree on how substantial a component Yongbyon is in the entire North Korean nuclear program.) Taking the facility out means “critically crippling North Korea’s nuclear capacity,” the official said.