Barricades are set up in front of Tongil Bridge in Paju, Gyeonggi Province, in this Sept. 24 photo. Yonhap

By Kang Seung-woo

A series of moves regarding North Korea are raising speculation that talks for a declaration to officially end the Korean War are gaining momentum.

According to sources, Park Jie-won, head of South Korea's National Intelligence Service (NIS), sat down for talks in Seoul, Monday, with Avril Haines, the U.S. director of national intelligence.

Although details of their discussion were not made public, they were said to have talked about President Moon Jae-in's proposal for a declaration to formally end the war, and a subsequent push by Seoul and Washington to bring Pyongyang back to denuclearization talks.

The two Koreas are still technically at war, as the 1950-53 conflict ended with an armistice, not a peace treaty, and Moon suggested once again in his United Nations speech in September that the two Koreas and the United States, probably joined by China, declare a formal end to the war.

In addition, the chief nuclear negotiators of the three countries are set to hold a trilateral meeting in Washington, D.C., Tuesday (local time), further fueling conjecture that an "end-of-war" declaration may be high on the agenda.

"I expect more in-depth discussions on various issues at the working level, including the end-of-war declaration," Noh Kyu-duk, Seoul's top nuclear envoy, told reporters at Dulles International Airport, Saturday.