The United States recently opened a small Marine outpost in northern Iraq and it has already come under fire from the Islamic State (IS) extremist group.
A U.S. Marine was killed two days ago in a rocket attack at the base, called Firebase Bell, the first U.S. base in Iraq since U.S. President Barack Obama pulled U.S. forces out of the country four years ago.
Obama has pledged to avoid a large-scale U.S. ground deployment in Iraq and to focus on enabling local forces to fight IS. But the U.S. military has become increasingly involved on the ground, sending in special forces since last year and now stationing as many as 200 soldiers from the 26th Marine Expeditionary Unit at the base.
The base's existence was meant to be kept secret until it was deemed operational, the U.S. military said, but IS quickly learned it was there.
Also despite its quiet beginnings two weeks ago, the base caught the attention of Iranian-backed Shi'ite militia which are also fighting IS. They are hostile to the increased presence of Americans, and have vowed to treat U.S. Marines deployed there as "forces of occupation."
The radical Sunni IS wasted no time targeting the base, launching an attack with Katyusha rockets on March 19 that killed Marine Staff Sergeant Louis Cardin and injured others in Cardin's company-sized detachment.
Obama expressed condolences over Cardin's death at a news conference as he visited Cuba for the first time on March 21.
"It's a reminder that even as we embark on this historic visit, there are U.S. armed service members who are sacrificing each and every day on behalf of our freedom and our safety, so I'm grateful to them," the president said.
Colonel Steve Warren, spokesman for the U.S.-led coalition in Baghdad, said the base was attacked again on March 21, this time by a squad of IS fighters who got close enough to the base to stage a failed attack with small arms.
He said no Marines were killed or wounded, but two IS fighters were killed in that attack.
"We are continuing to improve our fighting position, so to speak, to ensure that we've got the best ability to protect ourselves," Warren told a Pentagon news briefing.
He said the base should not be considered a combat outpost because it is located behind the front lines and is not initiating combat with the militants.
"Their primary mission is to protect, obviously, Americans," Warren said, referring to the U.S. advisers at a nearby Iraqi base near Makhmour.
U.S. military officials said there is currently no plan for the Marine artillery unit to be used in any offensive mission to retake Mosul, but they wouldn't rule it out.