US President Joe Biden says Washington is prepared to take additional measures following a series of attacks by Iran-linked groups targeting US forces in Iraq and Syria.

Early on Friday, US fighter jets carried out airstrikes in eastern Syria, targeting locations associated with Iran's Revolutionary Guard Corps. The strikes were a response to a barrage of drone and missile attacks against US bases and personnel in the region that began the previous week.

In a letter addressed to the new House Speaker Mike Johnson, Biden made it clear that the recent strikes were executed with the aim of establishing deterrence.

“The strikes were intended to establish deterrence and were conducted in a manner to limit the risk of escalation and avoid civilian casualties. I directed the strikes in order to protect and defend our personnel, to degrade and disrupt the ongoing series of attacks against the United States and our partners, and to deter Iran and Iran-backed militia groups from conducting or supporting further attacks on United States personnel and facilities,” read his letter.

US Defense Secretary Lloyd Austin, in a statement, described the precise self-defense strikes as a response to a prolonged series of mostly unsuccessful attacks on US personnel in Iraq and Syria by Iranian-backed militia groups, commencing on October 17.

Meanwhile, on Friday, the IRGC-affiliated news agency, Tasnim, reported that gunmen in eastern Syria fired ten rockets at a base housing American troops in retaliation for the US airstrikes. A US official confirmed the rocket attack, noting that there were no reported casualties.