Reuters reports: Syrian rebels said on Friday the assassination of one of their top commanders by al Qaeda-linked militants was tantamount to a declaration of war, opening a new front for the Western-backed fighters struggling against President Bashar al-Assad’s forces.

Rivalries have been growing between the Free Syrian Army (FSA) and the Islamists, whose smaller but more effective forces control most of the rebel-held parts of northern Syria more than two years after pro-democracy protests became an uprising.

“We will not let them get away with it because they want to target us,” a senior FSA commander said on condition of anonymity after members of the Islamic State of Iraq and Levant killed Kamal Hamami on Thursday.

“We are going to wipe the floor with them,” he said.

Hamami, also known by his nom de guerre, Abu Bassir al-Ladkani, is one of the top 30 figures on the FSA’s Supreme Military Command. His killing highlights how the West’s vision of a future, democratic Syria is unraveling.