U.S. Deputy Secretary of State Stephen Biegun said his talks on Monday with his South Korean counterpart Lee Do-hoon were "creative."
He said they discussed "constructive" ways to continue advancing their diplomacy on the Korean Peninsula.
On North Korea, Biegun urged Pyeongyang to engage in talks, saying Seoul and Washington cannot do it by themselves.
The two sides also discussed the killing last week of a South Korean national by North Korean soldiers.
They also reportedly discussed issues related to denuclearization on the Korean Peninsula, which may have included the declaration of an official end to the Korean War.