Fighters with al Qaeda affiliate Jabhat al-Nusra complete their training in the Qalamoun border region between Syria and Lebanon, April 29, 2015 Qalamoun Correspondent/ Jabhat al-Nusra

Forces aligned with the Syrian regime made major gains on Monday as the battle against al Qaeda’s Syrian branch continues on the border between Lebanon and Syria. The battle is likely to make major changes to the landscape of control in Syria and has now threatened to irreversibly drag Lebanon into the conflict.

Hezbollah and the Syrian army pushed out rebel fighters from a strategic hill in the Qalamoun border region on Monday. Ras al Maara overlooks the Lebanese border and gives pro-regime forces access to other rebel strongholds in the area and control over a major rebel supply line that leads to the Damascus suburbs.

On Monday in Syria, pro-regime forces seized the Ma’br al-Kharbah border crossing, effectively cutting off a rebel supply line that ran from the Damascus suburb town al Zabadani to the mountainous Qalamoun region. Because of the town’s proximity to the Lebanese border, rebels were believed to use the supply line to smuggle resources from Lebanon into Syria and vice versa.

Over the weekend, sources close to Lebanon’s armed political group Hezbollah claimed that the group raided one of the largest Nusra training camps in Al-Juba, a rugged and desolate region near the Lebanese border.

The Syrian army and Hezbollah have been fighting Syrian opposition forces led by al Qaeda’s Jabhat al-Nusra on both the Lebanese and Syrian sides of the border for the past week, and both factions have incurred casualties.

On Monday, two Nusra commanders were reportedly killed, including Abu Shuwaikh, the group’s commander for military operations in Ras al Maara, according to Hezbollah’s news outlet al-Manar.

At least three Hezbollah fighters have been killed since clashes began last Monday, although rebel sources claim that the number is much higher. Over the weekend, Lebanese Hezbollah fighters Syed Hassan Mohammad Mousawi, Basel Mohammad Basmeh and Abbas Hassan Yaseen were reportedly killed.