President Joe Biden has said on Sunday that the United States will "respond" to actions Iran has taken against Washington's interests, including drone strikes.

“With regards to the issue of how we’re going to respond to their actions against interest of the US, whether they are drone strikes or anything else, is we’re going to respond,” Biden said in a press conference following the G20 summit in Rome.

A Us base in Syria came under attack recently with drones suspected to have been launched by Iran-backed militias.

Officials said on October 25 that the US believes that Iran resourced and encouraged the attack, but that the drones were not launched from Iran. They were Iranian drones, and Iran appears to have facilitated their use, officials said, speaking on condition of anonymity to discuss details that have not been made public.

Iranian backed militias have also attacked bases hosting US troops in Iraq, recently using drones more often than rockets.

The US Treasury Department on Friday sanctioned two senior members of Iran’s Revolutionary Guard (IRGC) and two affiliated companies for supplying lethal drones to insurgent groups in Iraq, Lebanon, Yemen, and Ethiopia.

Biden's threat comes as the US and its European allies urge Iran to return to nuclear talks aimed at restoring the 2015 Iran deal.