In January 2014, rebels affiliated with the Islamic Front and the US-trained Free Syrian Army[65] launched an offensive against ISIL militants in and around the city of Aleppo, following months of tensions over ISIL's behavior, which included the seizure of property and weapons from rebel groups, and the arrests and killings of activists.[66][67] Months of clashes ensued, causing thousands of casualties, with ISIL withdrawing its forces from Idlib and Latakia provinces and redeploying them to reinforce its strongholds in Raqqa and Aleppo.[68] It also launched an offensive against all other opposition forces active in the eastern province of Deir ez-Zor, on the border with Iraq.[69][70] By June 2014, ISIL had largely defeated its rivals in the province, with many who had not been killed or driven away pledging allegiance to it.[71][72]