U.S. Special Representative for North Korea Stephen Biegun is now believed to have arrived in Pyongyang for working-level talks with his North Korean counterpart.

The envoy is said to have left Osan Air Base in the South at around nine Wednesday morning for an hour-long flight across the Yellow Sea into the North Korean capital.

Biegun is slated to meet with his North Korean counterpart Kim Hyok-chol, a former ambassador to Spain, to finalize details for the upcoming second U.S.-North Korea summit. 

The two sides are expected to focus their discussions on North Korea's denuclearization and corresponding measures by the U.S. 

It is, however, undecided whether Biegun will meet North Korean leader Kim Jong-un during his visit.