American military officials announced that they are planning an operation in April or May to free Iraq's second-largest city, Mosul, from the group that calls itself the Islamic State, or ISIS. The extremist group has controlled the city since June, and the Pentagon says up to 25,000 Iraqi troops will take part in an offensive to reclaim the city.
Kurdish fighters will be a key part of this operation. The Kurds are a close U.S. ally in this conflict and have already driven ISIS out of other areas in northern Iraq.