Israel's presence has been replaced by Lebanese military.
Centcom's leader Erik Kurilla was "present at the implementation", it is announced in a statement.
The idea behind the ceasefire agreement is that Israel's forces will withdraw from southern Lebanon during a 60-day transition period, and that Iran-backed Hezbollah will withdraw northwards. In a buffer zone, the UN's existing mission Unifil will hold positions together with Lebanon's regular but relatively weak army.
Since the ceasefire began in November, both sides have accused each other of breaking it.
