Syrian state television has reported that Syrian forces have captured the historic town of Qala'at al-Hosn near the Lebanese border, after days of intense clashes with opposition fighters.
Reports also say Syrian troops took control of the famous Crusades-era castle of Crac des Chevaliers in Qala'at al-Hosn.
The Lebanese television station al-Mayadeen aired footage of Syrian troops raising the national flag on the hilltop perch of the Crac des Chevaliers, a UNESCO World Heritage site. The structure appeared intact.
The capture of Qala'at al-Hosn, if independently confirmed, would mark a major victory for the Syrian army, which has been advancing on the opposition in efforts to secure towns and villages along the Lebanese border.
The rebels have supply lines along the border.
Also Thursday, U.N. aid trucks crossed from Turkey into Syria for the first time, a step relief officials hope will provide more humanitarian aid to the country's most desperate areas.
The U.N. regional humanitarian coordinator, Nigel Fisher, said the convoy was destined for the northern Syrian city of Qamishli and carried supplies for hundreds of thousands of people.
Last month, the U.N. Security Council called for Syrian authorities and rebels to allow prompt access of humanitarian supplies across front lines and borders by the most direct routes. Syria granted its approval to the opening of the border crossing.