The Pentagon said Thursday that two senior Islamic State leaders were killed in a U.S. airstrike in the Iraqi city of Mosul on June 25.

The Pentagon said the airstrike killed deputy war minister Basim Muhammad Ahmad Sultan al-Bajari and a military commander identified as Hatim Talib al-Hamduni.

The announcement comes after a U.S. official said earlier this week that at least 250 ISIS militants were killed in U.S.-led coalition airstrikes targeting Islamic State convoys.

Col. Christopher Garver said the first convoy was spotted southwest of Fallujah in an area with known ISIS influence. Iraqi Security Forces fought the militants on the ground, he said, before coalition strikes destroyed some 55 vehicles.

The official said a second convoy formed east of Ramadi later Wednesday before coalition and Iraqi jets launched more strikes. He said that air assault destroyed nearly 120 ISIS vehicles, but in both attacks, Iraqi Security Forces destroyed more.

The fall of Fallujah means that Mosul, Iraq's second largest city, is the terror group's only remaining urban stronghold in Iraq after Iraqi forces recaptured Fallujah.

Islamic State has suffered a string of territorial losses in Iraq but the group continues to carry out large-scale militant attacks in the capital, Baghdad, and other territory far from the front-lines.

The U.N. children's fund warned Thursday that the ISIS surge in Iraq and the military operation to route the extremist group from captured territory have had a "catastrophic impact," with some 4.7 million Iraqi children in need of humanitarian assistance.

UNICEF warned that 3.6 million Iraqi children are at "serious risk" of death, injury, sexual violence, abduction and recruitment into armed groups, and called on warring parties in Iraq to protect their rights. It said that the number of children in Iraq at serious risk of death or wartime exploitation had increased by 1.3 million in the past 18 months.

"Children in Iraq are in the firing line and are being repeatedly and relentlessly targeted," said Peter Hawkins, UNICEF's Iraq representative. "We appeal to all parties for restraint and to respect and protect children.  We must help give children the support they need to recover from the horrors of war and contribute to a more peaceful and prosperous Iraq."

The airstrikes come days after the triple suicide bombing at Istanbul's Ataturk Airport that killed more than 40 people. ISIS is considered the prime suspect, according to top U.S. officials.

Fox News' Lucas Tomlinson and the Associated Press contributed to this report.