South Korea expects the long-stalled international negotiations on North Korea’s nuclear programs to resume next month, the country’s chief negotiator said Friday.

Kim Sook made the prediction following recent progress the United States and North Korea made in efforts to resolve a key dispute that has deadlocked the six-nation nuclear talks.

“If consultations proceed smoothly, I expect the six-party talks will resume in June,” Kim told reporters during a briefing on the outcome of his trip to China, the host of the disarmament talks. “We’re conducting consultations with the first half of June in mind.”

North Korea agreed in a deal last year to shutter and disable its main nuclear reactor and fully account for its nuclear activities as part of the process of abandoning its nuclear programs for economic and political rewards.

But the landmark deal reached an impasse as Washington and Pyongyang bickered over how to address suspicions that the North pursued a uranium-based nuclear program and transferred nuclear technology to Syria. Pyongyang has rejected the suspicions.

The U.S. agreed last month to resolve the dispute in a way that requires North Korea to only acknowledge those concerns and to set up a system to verify that the country does not conduct such activities in the future.

That concession led to Pyongyang handing more than 18,000 pages of sensitive nuclear records over to Washington last week. U.S. officials said this week that the technical logs from the North’s now-shuttered main nuclear reactor appear credible.

Kim said he would travel to Washington on Sunday for talks with his U.S. and Japanese counterparts.

The six-party talks, involving China, Japan, the two Koreas, the U.S. and Russia, were last held between late September and early October.