In mid-2014, an international coalition led by the United States intervened against ISIL in Syria and Iraq with an airstrike campaign, in addition to supplying advisors, weapons, training, and supplies to ISIL's enemies in the Iraqi Security Forces and Syrian Democratic Forces. This campaign reinvigorated the latter two forces and damaged ISIL, killing tens of thousands of its troops and reducing its financial and military infrastructure. This was followed by a smaller-scale Russian intervention exclusively in Syria, in which ISIL lost thousands more fighters to airstrikes, cruise missile attacks, and other Russian military activities and had its financial base further degraded. In July 2017, the group lost control of its largest city, Mosul, to the Iraqi army, followed by the loss of its de facto political capital of Raqqa to the Syrian Democratic Forces. By December 2017, the Islamic State controlled just 2% of its maximum territory (in May 2015). In December 2017, Iraqi forces had driven the last remnants of the Islamic State underground, three years after the group captured about a third of Iraq's territory. By March 2019, ISIL lost one of their last significant territories in the Middle East in the Deir ez-Zor campaign, surrendering their "tent city" and pockets in Al-Baghuz Fawqani to the Syrian Democratic Forces after the Battle of Baghuz Fawqani.