North Korea's leader Kim Jong Un (L) bids farewell to South Korean President Moon Jae-in (R) on Moon's departure from North Korea at Samjiyon airport on September 20, 2018 in Samjiyon, North Korea.

Yonhap said the United States had previously demanded 1.13 trillion won (US$1 billion) from South Korea.

The U.S. State Department senior adviser for security negotiations and agreements, Timothy Betts, met Kang before signing the agreement on behalf of the United States, and told her the money represented a small but important part of South Korea's support for the alliance.

South Korea has signed a new deal with the United States on how much Seoul should pay for the U.S. military presence on its soil after a previous deal lapsed amid President Donald Trump's call for Seoul to pay more.

Yonhap quoted South Korea's presidential office as saying that Biegun planned to meet the North Koreans again in an Asian country next week.

Siegfried Hecker, a former director of the U.S. Los Alamos weapons laboratory and one of the report's authors, said satellite imagery showed North Korea's production of bomb fuel continued in 2018.

The president had been harping about South Korea not paying its fair share since the 2016 campaign, making this new agreement a clear victory for his policy of getting other nations to pay more for USA force protection.

The allies worked to finalize an agreement in order to minimize the impact on South Koreans working on USA military bases, and focus on nuclear talks ahead of a second U.S.

North Korea is expected to announce its candidate city later this week - the likely choice is its capital Pyongyang - before or during the International Olympic Committee meeting, Seoul officials told AFP.

The disagreement had raised the prospect that Trump could decide to withdraw at least some troops from South Korea, as he has in other countries like Syria.

Officials say a jointly-hosted Olympics is an opportunity for sports diplomacy to bring stability to the Korean peninsula, but its feasibility is dependent on North Korea's denuclearization plans, which will be discussed during upcoming talks between Kim Jong-un and U.S. President Donald Trump in Hanoi.

Abrams downplayed the impact of curbing those high-level exercises on US and South Korean troops' combat readiness, saying servicemembers have continued to conduct training exercises together on smaller scales. After the meeting, Trump suspended major joint military exercises with South Korea.

But both sides worked to hammer out a deal to minimise the impact of the lapse on South Korean workers on US military bases, and focus on nuclear talks ahead of a second US-North Korea summit, Seoul officials said. "These capabilities continue to hold the United States, [South Korea] and our regional allies at risk".

The South Korean Parliament has to approve the agreement before it becomes final. Most U.S. troops were withdrawn in 1949 but they returned the next year to fight alongside South Korea in the 1950-53 Korean War.