Tehran has denied any involvement in a drone strike that killed three US troops at a base in Jordan, near the border with Syria, after US President Joe Biden blamed Iran-backed militia and vowed revenge.

In a statement published by the state news agency Irna, Tehran’s UN mission said: “Iran had no connection and had nothing to do with the attack on the US base,” adding: “There is a conflict between US forces and resistance groups in the region, which reciprocate retaliatory attacks.”

Saturday’s unmanned aerial drone attack on the military outpost Tower 22 was the first deadly strike against US forces since the Israel-Hamas war erupted in October and sent shock waves throughout the Middle East.

Responsibility for the strike was claimed by the Iranian-backed umbrella group Islamic Resistance, which have long been trying to drive the US troops out of Iraq and Syria, and have used the war in Gaza as the backdrop to intensify these efforts and broaden the battleground.

US forces have faced a near-daily barrage of drone and missile strikes in Iraq and Syria since the 7 October attack on Israel by Hamas. But this incident draws the US much closer to a direct conflict with Iran, an outcome both sides insist they wish to avoid, but may now be unable to prevent as the incidents proliferate and escalate in impact.