Defense Secretary Ashton Carter has said the United States will ramp up attacks on Islamic State jihadists in Syria and Iraq, including action on the ground.
Testifying before the Senate Armed Services Committee on Tuesday (local time), Carter said he expected more actions like the one last week that freed dozens of captives but left an American commando dead in Iraq.
"We won't hold back from supporting capable partners in opportunistic attacks against ISIL, or conducting such missions directly, whether by strikes from the air or direct action on the ground," Carter said.
He did not elaborate on what he meant by "direct action on the ground".
The Obama administration opposes committing US ground forces to Syria, but currently some 3500 US forces are in Iraq in a "train and advise" capacity to support local forces as they fight IS jihadists.
Carter's statement appears to be a doubling-down of comments he made last week following the raid in which US Special Operations forces and Kurdish peshmerga troops stormed an IS-run prison near Hawijah in northern Iraq, freeing some 70 captives who were facing imminent execution.
Following the raid, in which Master Sergeant Joshua Wheeler became the first American serviceman to die in action in Iraq since 2011, Carter said he expected "more of this kind of thing".
Carter told senators the US was focusing its efforts on the IS stronghold of Raqqa in northern Syria and will boost support for rebel groups fighting the jihadists.
"We expect to intensify our air campaign, including with additional US and coalition aircraft, to target ISIL with a higher and heavier rate of strikes," Carter said, using an alternate acronym for IS.
"This will include more strikes against ISIL high-value targets as our intelligence improves," he added.