De Alencar, originally from Edgewood, Md., was assigned to the 1st Battalion of the 7th Special Forces Group based out of Florida.
A post on the Joppatowne High School Alumni page, first reported by the Baltimore Sun, said De Alencar was a 1998 graduate of the school and leaves behind a wife and five children.
U.S. and Afghan forces have been fighting the Islamic State in Afghanistan’s restive east since 2015. Soldiers from elite Ranger battalions as well as Green Berets have conducted multiple large-scale operations to push the militants out of the country, while airstrikes have targeted the group’s leadership.
The Taliban, the insurgent group that has fought the United States and the Afghan government since 2001, has also routinely clashed with the Islamic State.
On Thursday, Navy Capt. Bill Salvin, a spokesman for U.S. forces in Afghanistan, told the Associated Press that the Islamic State in Afghanistan had lost more than two-thirds of its territory and had 800 fighters spread between two provinces. Salvin added that since the start of 2017, the Pentagon had carried out more than 450 strikes against the Islamic State in Afghanistan and killed more than 200 militants. In December, the spokesman for U.S. forces in Afghanistan, Brig. Gen. Charles Cleveland, said that Islamic State forces in the country had been reduced from 3,000 to 1,000.
The incident marks the first combat death in Afghanistan for 2017. Last month, three Special Operations soldiers were wounded during an apparent insider attack in Helmand Province, and 2016 saw the death of 10 U.S. service members by hostile fire and bomb attacks, both by the Taliban and the Islamic State. More than 1,800 U.S. troops have died in combat in Afghanistan since 2001, according to Pentagon statistics.
There are 8,500 U.S. troops still in Afghanistan, split between supporting the Afghan military and conducting counterterrorism operations. U.S. military officials have classified the conflict as a stalemate and requested thousands more troops to provide more help to the fledgling Afghan military.
This post has been updated.