The United States has roughly 900 troops in Syria to fight the Islamic State group, but they also currently face a familiar adversary: Iran.

Most recently, the U.S. government has blamed Iranian-backed groups for several attacks against American service members deployed to Syria, including a March 23 suicide drone attack on a coalition base in Hasakah that killed an American contractor and wounded five U.S. service members.

U.S. intelligence officials quickly determined that the drone was “of Iranian origin,” the Defense Department announced that day.

In response to the attack, the U.S. military launched airstrikes on March 23 against facilities in eastern Syria that were used by “groups affiliated with Iran’s Islamic Revolutionary Guards Corps (IRGC),” Defense Secretary Lloyd Austin said in a statement.

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The following day, U.S. forces at two bases in northeast Syria came under rocket attacks, and one U.S. service member was injured, said Army Col. Joe Buccinio, a spokesman for U.S. Central Command.

“Our current assessment is that these rocket attacks were conducted by IRGC-affiliated groups, that this rocket attack was done in an effort to retaliate from last night’s attacks,” Air Force Brig. Gen. Patrick Ryder, a Pentagon spokesman, told reporters on March 24.

So far, U.S. officials have not publicly identified which group that may be responsible for the recent attacks against U.S. troops. Information about the Iranian-backed group believed responsible for the March 23 drone attack is classified, according to U.S. Central Command.

The first U.S. service members arrived in Syria in October 2015 to help the Kurdish-led Syrian Democratic Forces destroy ISIS’s caliphate. Although ISIS lost its last remaining territory in 2019, U.S. troops continue to battle an ISIS insurgency in Syria and Iraq. As recently as this February, four U.S. service members and a military working dog were injured during a raid near Deir ez-Zor Syria that resulted in the death of a senior ISIS leader.

Separately, Iran has sent fighters from across the Middle East to support Syrian President Bashar al-Assad amid the country’s ongoing civil war. Iran has not only sought to defend a friendly regime, but it has also used the Syrian civil war to vastly increase its influence in the country long after the war’s eventual end.

Syria plays an integral part of Iran’s strategy to become the biggest power in the Middle East, expel all U.S. forces from the region, and destroy Israel, said Nichols Carl, the Middle East Portfolio Manager at the American Enterprise Institute think tank in Washington, D.C.

“Iran is deeply committed to trying to entrench itself – economically, politically, militarily socioculturaly – as deep into Syria as it possibly can, because it wants to stay there in the long run,” Carl told Task & Purpose.

For years, Iran has sent Shia militia groups from Iran, Iraq, Lebanon, Afghanistan, Pakistan, and possibly Yemen to fight for the Syrian regime and preserve Iranian interests, he said. It’s not clear exactly how many Iranian-backed fighters are currently in Syria.

Iran is also “laser-focused” on driving all U.S. troops from both Syria and Iraq, Carl said. The Pentagon reported in 2019 that Iranian-backed militants killed 603 U.S. troops in Iraq between 2003 and 2011.

The recent drone and rocket attacks and the U.S. airstrikes represent the heaviest reported fighting between U.S troops and Iranian proxy forces in Syria since this past August when an unspecified number of AC-130 gunships and AH-64 Apache attack helicopters struck Iranian-backed groups after an attack on the Green Village.

Despite the recent attacks, the U.S.-led coalition will continue its mission to defeat ISIS in Syria, said Army Maj. Matthew McFarlane, the commanding general of Combined Joint Task Force – Operation Inherent Resolve.

“The Coalition is focused on our D-ISIS [defeat ISIS] mission, but we monitor threats across Iraq and Syria very closely,” McFarlane said in a statement to Task & Purpose. “We stand prepared to address any of these threats that prevent us from pursuing our D-ISIS mission.”

President Joe Biden has also warned Iran that the United States would respond to any further attacks against American troops.

“The United States does not – does not, I emphasize – seek conflict with Iran, but be prepared for us to act forcefully to protect our people,” Biden said during a March 24 news conference in Canada.

When a reporter asked if the United States would inflict a higher cost on Iran if attacks against U.S. troops continued, Biden replied, “We are not going to stop.”

UPDATE: 03/27/2023; this story was updated on March 27 after Army Col. Joe Buccino, a spokesman for U.S. Central Command, said that one service member was injured by a March 24 rocket attack in Syria.

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