The U.S. military informed its counterparts in Baghdad on Monday it is preparing for "movement out of Iraq."
Operation Inherent Resolve
The incident is under investigation.
The Defense Department has identified a Marine Raider killed in Iraq while supporting the joint mission to defeat ISIS.
U.S. Central Command has rejected a commander's assertion that Iran posed "no increased threat" to U.S. troops.
Spc. Ryan Riley, 22, died in Ninawa province, Iraq.
In addition to U.S. and coalition strikes, Iraqi fighter aircraft have also attacked ISIS targets inside Syria recently.
Ambassador James Jeffrey told Russian media that some of the clashes had involved shooting and some had not.