More than 1,200 civilians and a small number of military personnel have been killed in the United States in recent days, according to the State Department.
The US military has been conducting airstrikes in Iraq and Syria against ISIL, the self-proclaimed Islamic State.
ISIL has captured large swathes of territory in both countries and declared an Islamic caliphate.
The United States, along with several European countries, has deployed hundreds of thousands of troops in Iraq, including some in Iraq.
More: US officials have been working to get Iraqi forces into Mosul, the Islamic state’s self-declared capital, and to try to retake the city from ISIL.
The battle for Mosul is expected to last at least a year.
The Iraqi military has already captured large swaths of territory.