The U.S. carried out airstrikes targeting two facilities linked to Iranian-backed militias in eastern Syria following a series of drone and rocket attacks against U.S. forces in the region, Defense Secretary Lloyd Austin said Thursday.

The airstrikes, directed by President Joe Biden, follow injuries to 21 American troops during 10 drone and rocket strikes in Iraq and three in Syria by Iran-backed militia groups between Oct. 17 and Oct. 24. One American, a U.S. contractor, died from a cardiac incident while sheltering in place during one of the attacks.

Austin, in a statement, said the U.S response makes clear "the United States will not tolerate such attacks and will defend itself, its personnel, and its interests."

"The United States does not seek conflict and has no intention nor desire to engage in further hostilities, but these Iranian-backed attacks against U.S. forces are unacceptable and must stop," Austin said. "Iran wants to hide its hand and deny its role in these attacks against our forces. We will not let them."

Austin added that if Iran's proxies continue to attack U.S. forces "we will not hesitate to take further necessary measures to protect our people."

Biden, during a Rose Garden news conference Wednesday, warned Iran's ayatollah that "if they continued to move against those troops, we will respond and he should be prepared."

Austin said the two facilities in Syria were used by Iran’s Islamic Revolutionary Guard Corps (IRGC) and affiliated groups.

In the aftermath of the Oct. 7 Hamas attack on Israel, Biden also warned Iran to "be careful" and not exploit Israel's war with Hamas to create a wider Middle East conflict.

But the White House has sought to separate the Iranian-backed militia strikes - and subsequent U.S. response - from the Israel's fighting in Gaza.

American troops have been in the region for decades, fighting ISIS, and working to prevent the terror group's reemergence, Biden said on Wednesday.

"They are separate and distinct from the ongoing conflict between Israel and Hamas, and do not constitute a shift in our approach to the Israel-Hamas conflict," Austin said. "We continue to urge all state and non-state entities not to take action that would escalate into a broader regional conflict."