Facing deadly Iranian drone attacks across the Middle East, the US military has been rushing defensive systems into the region while adjusting to a threat that has come to dominates modern battlefields and carries echoes of a weapon that haunted service members during the 20 years of the war on terror.

FBI memo warning that Iran may try to launch drones at California in a seaborne "surprise attack" raised concern Wednesday — but officials tell CBS News there is no known, specific threat underpinning it.

California Gov. Gavin Newsom says there's no imminent threat to the state from Iran. ABC News says the FBI warned California that Iran had aspired to send drones to the West Coast in retaliation for war.

“I think it is a cautionary warning, and I think it's one that we should take heed with."

Explosions and drone activity were reported near the US Embassy in Baghdad as the Iran conflict escalates. Videos show air defences intercepting projectiles, while a suspected drone struck close to the compound,

Pakistan’s president on Saturday warned neighboring Afghanistan’s Taliban government that it had “ crossed a red line ” by launching drone attacks on civilian areas in Pakistan and said the administration in Kabul has brought “grave consequences upon itself.

The attack hit four districts, damaging residential buildings, educational institutions and critical infrastructure, officials said.