WASHINGTON (AP) — After months of trading insults and threats of nuclear annihilation, President Donald Trump agreed to meet with North Korean leader Kim Jung Un by the end of May to negotiate an end to Pyongyang’s nuclear weapons program, South Korean and U.S. officials said Thursday. No sitting American president has ever met with a North Korea leader.

The meeting would be unprecedented during seven decades of animosity between the U.S. and North Korea. The countries remain in a state of war because the 1950-53 Korean War ended with an armistice and not a peace treaty.

“Great progress being made,” Trump tweeted after the South Korean national security director, Chung Eui-yong, announced the plans to reporters in a hastily called appearance on a White House driveway.

Trump added that sanctions will remain in place until there’s a deal.

Trump took office vowing to stop North Korea from attaining a nuclear-tipped missile that could reach the U.S. mainland, a goal that Pyongyang is on the cusp of reaching. He’s oscillated between threats and insults directed at Kim that have fueled fears of war, and more conciliatory rhetoric.

The historic announcement comes during a period of unparalleled tumult in the West Wing, with the president’s policy agenda stalled and morale sinking as staff departures proliferate and disrupt efforts to instill more discipline and order.