Speaking on condition of anonymity, the official said U.S. and international forces were attacked at two sites in northeastern Syria with multiple rockets and a one-way attack drone.
In Iraq, multiple one-way drones were launched at the Ain Al-Asad air base west of Baghdad and a drone was launched at a base that houses U.S. forces near Irbil airport in northern Iraq.
A group calling itself the Islamic Resistance in Iraq, which analysts say is a catch-all for several Iran-aligned, Iraqi-armed groups, had claimed responsibility for attacks on those locations earlier in the day.
The attacks came the day after the U.S. struck the Iran-aligned Kataib Hezbollah, or KH, armed group south of Baghdad in an attack that KH said had left eight members dead.
The attack was condemned by the Iraqi government as escalatory and a violation of sovereignty.
U.S. officials said the United States had struck Iran-aligned groups after an escalation in their attacks that have targeted U.S. and international forces dozens of times since October 17, 10 days after the Israel-Hamas war began.
As of Thursday, there had been 36 attacks in Iraq and 37 in Syria, the U.S. military official said.