WASHINGTON – The conflict in north-east Syria escalated on Friday as Iran-backed militias launched a volley of rocket and drone attacks against coalition bases after American reprisals for a drone attack that killed a US contractor and injured six other Americans.

US President Joe Biden, speaking at a news conference in Canada, sought to tamp down fears that tit-for-tat strikes between the United States and militant groups could spiral out of control, while at the same time warning Iran to rein in its proxies.

“Make no mistake, the United States does not, does not, I emphasise, seek conflict with Iran,” Mr Biden said in Ottawa, Ontario, where he was making a state visit. “But be prepared for us to act forcefully to protect our people. That’s exactly what happened last night.”

The fighting, among the most serious in the area since 2019, threatens to upend recent efforts to de-escalate tensions across the wider Middle East, whose rival powers, including Iran and Saudi Arabia, have made steps towards rapprochement in recent days after years of turmoil.

The initial attack on Thursday came as US forces in north-east Syria were on high alert following 78 attacks by Iran-backed militias since January 2021.

But a self-destructing drone, which US officials said was of “Iranian origin”, managed to hit a coalition base anyway, killing the US contractor and wounding six other Americans.

Two US officials said the main air defence system at the base was “not fully operational” at the time, raising questions about whether the attackers had detected that vulnerability and exploited it, or just happened to send the drone at that time, according to people who spoke on condition of anonymity.

Brigadier-General Patrick Ryder, the Pentagon spokesman, said the air defence’s radar was working, but he declined to discuss any other details of the system, citing operational security and an investigation by the military’s Central Command.

It was unclear why the system was not fully functional and what difference that had made in defending the base.

The Avenger missile defence system at the base, called RLZ, may have been experiencing a maintenance problem, one of the US officials said.

After US intelligence analysts concluded that the drone was of Iranian origin, a claim the Pentagon made without any supporting evidence, the US retaliated by launching air strikes against militant sites linked to Iran’s Revolutionary Guard, Mr Ryder said. NYTIMES