On 7 May 2017, the Syrian Arab Army, led by the 5th Corps and Iranian-backed militias, launched an attack on the FSA in the Sabaa Biyar area of Homs province.

[46] The commander of the Lions of the East Army, Tlas al-Salama, said that Syrian warplanes had struck rebel outposts near the Syrian-Jordanian border after which his group fired missiles towards Khalhala airport.

In retaliation, the Syrian Air Force hit FSA convoys and their rearguard headquarters at the al-Tanf border crossing,[49] and on 12 May Iraqi Shi'ite militias launched an offensive from the east to drive the militants from the desert region.

[53] On 18 May, National Defense Forces, alongside the 5th and 7th Armored Divisions of the Syrian Army, advanced 35 kilometers into rebel-held areas in eastern As-Suwayda Governorate.

[21] Meanwhile, government forces were probing to determine how near they could get to al-Tanf and reached positions about 27 kilometers from the town,[54] when the lead portion of their advancing convoy was hit by US-led Coalition air-strikes.

[64][65] On 22 May, the Army captured the Al-Rahbeh area, 25 kilometers north of the Zuluf dam, with no direct clashes taking place, save for an artillery duel.

[66] Towards the end of the day, the Syrian Army reached positions six kilometers south of the newly captured Scientific Research Battalion, while other forces advanced east of the Zuluf Dam.

These advances, brought the Army close to completely encircling and cutting off rebel forces in the southeastern part of Damascus governorate from their comrades in and around al-Tanf.

[71][72] On 30 May, the Syrian Army, alongside the National Defense Forces and Iraqi paramilitary units, captured the Helba area in southeastern Homs province, thus coming within 50 km of the border with Iraq.

[75][76] Three days later, the Army reported it had captured three areas from ISIL south of Palmyra, creating the conditions for a simultaneous push towards both the T3 pumping station and Arak.

[85] On 9 June, government forces advanced eastwards and set up positions around 70 kilometers (43 miles) northeast of al-Tanf, thus reaching and securing a part of the Syrian–Iraqi border for the first time since 2015.

[citation needed] Later on that day, almost the entire 103rd Brigade of the Republican Guard was deployed to the area from the Latakia Governorate, to participate in an upcoming large-scale offensive to break ISIL's siege of Deir ez-Zor city.

[96] On 19 June, ISIL fighters reportedly stormed a military camp held by the Revolutionary Commando Army, resulting in the capture and subsequent execution of eight rebels.

[104] On 26 June, government forces made significant advances toward Abu Kamal,[105] and over the next two days captured more territory from ISIL in eastern Homs Governorate.

The next day Syrian Army pressed on towards Sukhnah, capturing most of al-Qalilat mountain chain northwest of al-Hail gas field, stating that they killed over 20 ISIL fighters.

[113][114] Despite an internationally agreed ceasefire,[115] on 10 July Syrian government troops and Iranian-backed militias initiated the second phase of Operation Big Dawn,[116] launching an assault upon eight rebel-held villages east of Khalkhalah airbase in a sparsely-populated, mainly Druze desert area, capturing the hilltop of Tal al-Asfar alongside several smaller hills overlooking the village of Al-Asfar.

[13] Over the next several days, by 13 July, the Syrian Army and its allies captured an additional 200 km2,[122] coming within 20 km from completely encircling a large rebel-held mountainous semi-desert area straddling across eastern Suwayda and Rif-Dimashq governorates.

[123][124] Following a short-lived ceasefire with the FSA in Syria's southwestern Badia region, brokered by Russia and the United States,[125][126] government forces started redeploying to the east of Palmyra for a new offensive.