The Lebanese army announced Tuesday that it had begun deploying to an area in the south, one of three "pilot zones" outlined in a deal with Israel to disarm Hezbollah.
The announcement came with Lebanese President Joseph Aoun visiting Washington, which sponsored the deal with Israel.
Israel invaded Lebanon during its recent war with Iran-backed militants Hezbollah, and it has continued to occupy parts of the country despite a ceasefire.
To date, Israeli troops have only controlled the outskirts of one of the so-called pilot zones, with their occupation of other areas yet to be addressed.
The Lebanese military already has a presence in the other two pilot zones.
"Military units began deploying this morning to Zawtar al-Garhbiya" in the Nabatieh region, the army said in a statement.
Lebanese media showed military vehicles, some flying the Lebanese flag, entering the village which sits on the edge of the what Israel has dubbed the "security zone".
Israel's invasion came after Hezbollah dragged Lebanon into the wider Middle East war in March with rocket attacks on Israel in support of Iran.
Lebanon and Israel signed their framework agreement last month which aims for Israel's gradual withdrawal from Lebanon and the disarming of Hezbollah, with Lebanon's army taking over security in the south.
Hezbollah has repeatedly rejected the deal and refuses to disarm, while there is no timetable for Israel's full withdrawal.
The US State Department on Monday evening announced that the Lebanese army had begun ensuring security in the villages of Zawtar al-Garhbiya, Froun and Srifa.
Israeli forces are not present in the latter two villages, which straddle the edge of the security zone, while they had deployed to the outskirts of Zawtar al-Garhbiya.
A US official called the moment "an opportunity for the Lebanese state to begin to reassert real control in areas historically dominated by Hezbollah".
The Israeli military, meanwhile, announced that it would "adjust its force posture in one of the pilot areas".
