The U.S. military said Thursday that it intentionally bombed a hospital in Mosul, Iraq as part of its efforts to "eradicate" Islamic State (ISIS) fighters.

The attack on the Al Salam hospital complex took place Wednesday at the request of Iraqi forces, with coalition aircraft using "precision-guided munitions," Air Force Col. John Dorrian, spokesperson for the U.S.-led coalition against ISIS, told reporters.

He said "it's very difficult to ascertain with full and total fidelity" that there were no civilian casualties, whether in the building targeted or elsewhere within the hospital complex.

ISIS fighters, Dorrian said, "were using the facility to fire heavy machine guns and rocket-propelled grenades at the Iraqi security forces in the area." The strike on the "normally protected facility" allowed the Iraqi forces "to fall back to a more defensible position," he said.

The "protection of civilians," he said later in the press conference, "has been a centerpiece, a foundational element of the campaign to liberate Mosul."

The military is not carrying out an investigation but rather an "assessment" of the strike, the spokesperson added.

The battle to reclaim Mosul from ISIS fighters, which began in October, has left civilians, including roughly 600,000 children, trapped and facing a worsening humanitarian situation.