Defeated Syrian rebels near the border with the Israeli-occupied Golan Heights are preparing to evacuate the region and cede control of the frontier to Bashar al-Assad, securing a key victory for the Syrian president, whose forces are on the verge of concluding a swift campaign to reclaim control of southern Syria.

Under the deal, the Syrian military will deploy once again to its pre-2011 positions along the Golan frontier, defined by the 1974 disengagement treaty with Israel.

Mirroring other agreements throughout the country, rebel fighters who do not want to reconcile with the Assad regime will be allowed to leave for opposition-controlled regions in the north near Turkey.

Those who wish to stay have to resolve their status with the government and may be drafted into the military in the future. All heavy weapons will be turned over to authorities.

The agreement was made public by Syrian state TV and the details were outlined by both a media outlet belonging to the Lebanese group Hezbollah, which is fighting alongside Assad, and the Syrian Observatory for Human Rights, a war monitor.

It marks a key milestone and victory for the Assad regime, which launched a major offensive a month ago to reclaim control of all of southern Syria – a region that includes Deraa, which borders Jordan, and Quneitra, which borders the Israeli-occupied Golan Heights. Deraa is considered the birthplace of the Syrian uprising, where protests against the regime’s torture of teenagers who scrawled anti-government graffiti in 2011 spread nationwide.

The campaign was sensitive because of Israel’s concerns that Iranian-backed militias fighting alongside Assad might establish a presence near the Golan Heights, the region seized by Israel in the 1967 six-day war and later annexed.

The US said in June that it would not intervene to protect the southern rebels, despite years of logistical, political and military support for them, a declaration that accelerated their surrender after a short but violent bombardment by regime forces backed by Russia.

Last week, dozens of displaced Syrians sought refuge in the Golan Heights from the continuing bombardment of their towns, but were turned back by Israeli border guards.

Forces loyal to Assad are preparing to establish complete control over Deraa and Quneitra, except for a sliver of territory under the control of Islamic State that is still under bombardment by the regime.

The fighting had displaced more than 300,000 people, but many returned to their homes after surrender deals in the area. The number of people fleeing the violence stands at about 200,000, including 140,000 near the Golan Heights.

The UN refugee agency on Friday appealed to all sides in the conflict to provide safe passage for those stranded in the country’s south-west, so they can receive aid and shelter.

Assad’s forces will likely turn to Idlib, the province controlled by Islamist rebels and al-Qaida-linked fighters, where hundreds of thousands of Syrians fleeing violence elsewhere and the advance of pro-regime troops have settled.

Ankara warned this week against any escalation in the region, which borders Turkey, and where Turkish observers are stationed to prevent an escalation in violence. An offensive there could cause a major humanitarian catastrophe and send a fresh wave of refugees into Turkey.