North Korea and the U.S. may hold two rounds of pre-summit talks this week in Vietnam ahead of their second summit set for next Wednesday and Thursday in Hanoi.

According to diplomatic sources in Washington on Monday, Alex Wong, the deputy assistant secretary for East Asian and Pacific Affairs for the U.S. State Department, departed for Vietnam on Sunday, while U.S. Special Representative for North Korea Stephen Biegun will leave on Wednesday.

Wong accompanied Biegun on his trip to Pyongyang earlier this month for working-level talks to prepare for the summit. 

There is speculation that Wong will hold preliminary talks with Pak Chol, the vice chairman of North Korea’s Asia-Pacific Peace Committee, on Tuesday in Vietnam to coordinate the summit agenda. Pak arrived in Vietnam on Saturday as part of the North Korean delegation preparing for the summit. 

Afterwards, Biegun is expected to hold a meeting with his North Korean counterpart Kim Hyok-chol later this week.

If Biegun departs for Vietnam on Wednesday, his meeting with Kim will likely come on Friday.