WASHINGTON — Senior U.S. officials arrived in Damascus on Friday for the first diplomatic mission to the Syrian capital since the fall of dictator Bashar al-Assad this month.

The U.S. delegation, led by Barbara Leaf, the senior State Department official for the Middle East, is expected to meet with members of the Hayat Tahrir Al-Sham (HTS) rebel group, according to a State Department spokesperson. The group is acting as the de facto government in Syria.

Those discussions are expected to…