A year after four Americans died in a bomb blast in northern Syria - the single deadliest day for the some 700 troops still there - another US solider has died.

A 22-year-old U.S. Army Reserve soldier identified by the Pentagon as Spc. Antonio Moore was killed Friday in a vehicle rollover accident.

Spc. Antonio Moore. US Army/AP

His combat engineering unit based out of North Carolina was conducting a route clearing operation in Deir Ezzor province in Syria's east, where US forces have been supporting Syrian Kurdish forces (SDF) in "securing the oil fields" — as President Trump has recently described the mission.

Though numbers have varied, most reports put current troops levels in Syria at over 500, with the AP in a new report saying 750 troops deployed in the country, citing Defense Department officials.

An official Army statement issued Saturday reads: “The 363rd Engineer Battalion is deeply saddened at the loss of Spec. Antonio Moore.” It continued: “Antonio was one of the best in our formation. He will be missed by all who served with him. We will now focus on supporting his family and honoring his legacy and sacrifice.”

Moore's reserve unit - 363rd Engineer Battalion, 411th Engineer Brigade, out of Knightdale, N.C. - was only somewhat recently established, in 2015, and includes only 100 service members.

US troops are present in Deir Ezzor (red above) and Hasakah provinces in the country's East.

Congressional critics of US policy in Syria have questioned the White House's unilaterally stationing troops in harm's way, with no war powers vote — concerns which have only grown after Trump's public remarks about "taking the oil" in Syria.

Meanwhile, the theater is growing more dangerous for the small American presence which is not wanted either by Syria, Russia, Turkey, or Iran. Concern has also grown that pro-Iran militias operating both in Syria and Iraq will seek to target US troops throughout the region and Washington's showdown with Iran grows more direct and confrontational.