As the rebels who ousted Syria’s longtime dictator, Bashar al-Assad, transition from insurgents to administrators, maintaining order in the streets of the capital has become a top priority.

Assad, old alliances have crumbled, and global powers are figuring out their relationships with Syria’s new de facto leaders.

The visits came a day after Sharaa — also known by his nom de guerre, Abu Mohammed al-Jolani — met with Turkish Foreign ...