Militants fighting for Jabhat al-Nusra, or al-Nusra Front, stormed Syria's government buildings in government-held Idlib Monday. It was the first time that the Sunni militant group, al Qaeda's Syrian offshoot, had entered the city since 2012; the government has held Idlib since then.

According to Syrian state television, the militants entered the city in the early hours of Monday morning and confronted government troops with heavy shelling, killing dozens of them. Directly following the early-morning attack, al-Nusra Front fighters proceeded to make their way further into the city, storming government-held buildings. On social media, the group said that it also seized two government tanks and captured 12 soldiers.

If Jabhat al-Nusra holds its offensive in Idlib, it could shift the power dynamic in the northern part of the country. Idlib sits on the road to Damascus and is located just south of Aleppo, the country's economic capital, which is currently in control of opposition forces led by the Free Syrian Army. If al-Nusra Front takes complete control of Idlib, opposition rebels will hold a large swath of land in the northern part of the country, blocking the government from transportation routes to Turkey and access to key military bases.

Despite Jabhat al-Nusra's gains in Idlib Monday, the offensive is likely to cause deep rifts between opposition rebels in the north. Rebels, though they are all fighting against President Bashar Assad, are also battling each other. Al-Nusra Front is vying for power and influence in the north -- but so is the Free Syrian Army. Both groups want to lead the opposition's fight against Assad. The emergence of the Islamic State group in Syria has only complicated that fight.