Iraqi forces scored a major victory against the self-declared Islamic State on Monday. ISIS fighters have reportedly retreated from the city of Ramadi, and they've abandoned the group's last stronghold in the city. The Iraqi troops captured the government complex on Sunday, reclaiming the area from the terrorist group. On Monday, Iraq's military declared that Ramadi had been "liberated" from ISIS's stronghold, the BBC News reports. The development is a big one for the Iraqi army — AFP called the success in Ramadi the "biggest victory since last year's massive jihadist nationwide offensive." AFP explains that while some ISIS members may still be in Ramadi, there is no more resistance to Iraqi forces. ISIS seized control of Ramadi, which is roughly 55 miles west of Baghdad, in May. Iraqi forces had been working to reclaim the city since November. The U.S.-led coalition had supported Iraq's efforts with more than 630 air strikes. Col. Steve Warren, a Baghdad-based spokesperson for the U.S. military, told The Associated Press that "the coalition will continue to support the government of Iraq as they move forward to make Ramadi safe for civilians to return and as the military moves to fight ISIL in other areas of the country."