PENTAGON - Pro-Syrian government forces hit by U.S.-led coalition airstrikes in an established deconfliction zone inside Syria were directed by Iran, U.S. Secretary of Defense Jim Mattis said Friday.
Mattis told reporters at the Pentagon the strikes were conducted in "self-defense" and were "necessitated by offensive movement with offensive capability of what we believe were Iranian-directed forces." He added that it was unclear whether Iranians were on the ground with the forces.
U.S. Central Command spokesman Major Josh Jacques said in an interview with VOA on Thursday that pro-Syrian government forces set up a convoy northwest of the al-Tanf army base — where U.S.-led coalition forces are training Syrian militias fighting Islamic State — with Syrian tanks, bulldozers, armored vehicles, artillery vehicles and technical vehicles, and began creating fighting positions for their tanks.
Coalition strikes destroyed one of the tanks, two front-end loaders, another piece of construction equipment and a tactical vehicle, according to a U.S. Central Command strike release.
Officials say some of the pro-Syrian government forces are still violating the deconfliction zone set up around the al-Tanf base. The zone has been established as the area within a 55-kilometer radius from the base.
"We're calling on them to withdraw from the deconfliction zone," Jacques told VOA.
'Every opportunity to leave'
Over several hours, the coalition flew aircraft through the airspace and fired missiles into the ground as "warning shots" near the pro-Syrian forces, but they continued building their positions, Jacques said.
The coalition also used a deconfliction hotline established between the U.S. and Russia to see if the Russians could get them to leave the area, but several apparent Russian attempts led to no change from the forces.
"It looks like the Russians tried to dissuade them," Mattis said Friday.
"After that, we couldn't do much else," Jacques said. "They had every opportunity to leave the area."
Syria has condemned the deadly coalition attack and said airstrikes near the border with Jordan are hampering efforts by the Syrian army and its allies to fight Islamic State.
Russia — a close ally of Syrian President Bashar al-Assad's government — called the airstrikes "unacceptable."
Syrian rebels hailed the coalition raids and encouraged further actions against the pro-Syrian government forces and Shi'ite militias who also are trying to gain control of the strategic border point.
"What happened today demonstrates that they cannot reach our territories," Al-Baraa Fares, a spokesman for the rebel group Maghaweer Al Thawra, told VOA. "When they tried, we informed the collation airplanes, which destroyed their convoys."
A U.S. official estimated that "possibly dozens of fighters" convoyed into the restricted area ahead of the airstrike. Another official put the number of pro-government fighters inside the deconfliction zone at a "couple hundred."
"The strike was not a change in policy," but rather an instance of the commander on the ground calling for force protection, according to a third official.
A statement from the coalition Thursday confirmed the deconfliction zone agreement remains in effect.
Jacques also said that Russia had agreed to call the United States to deconflict whenever they planned to operate in the area within 55 kilometers of the base. The Russians had used the hotline less than 24 hours before the Syrians violated the space.
"The line's been up and running," he noted.
The U.S. military says it does not communicate with pro-Syrian government forces and speaks with Russian forces only when needed to prevent miscalculations, since U.S. and Russian aircraft both conduct bombing missions in Syrian skies.
"We will never work with the Assad regime," Brett McGurk, the special presidential envoy for the counter-IS coalition, told Pentagon reporters Friday.
Anti-Islamic State initiative
Anti-IS coalition forces have been operating in the al-Tanf area for many months. Their focus has been to train and advise Syrian rebel groups on how best to capture key terrorist-controlled territories on the Syrian southern border with Jordan and Iraq.
The pro-Syrian government forces were 25 kilometers away from al-Tanf base when they were targeted by coalition planes, according to Fares.
Fares said the pro-Syrian government forces tried but failed to receive reinforcement from nearby Shi'ite militias.
Ahed Al Hendi from the VOA Extremism Watch Desk contributed to this report.