America is on alert for an attack on home soil by Iranian-backed terrorists, JD Vance, the US vice-president, has said.

Authorities are preparing for a possible attack after Donald Trump bombed Iran’s nuclear facilities on Sunday morning local time, with security at places of worship in major cities being increased.

Speaking to NBC’s Meet the Press, Mr Vance, claimed individuals “on the terrorism watch list” had been allowed to enter the country during Joe Biden’s administration.

“We feel very confident in our FBI and law enforcement that we’re on top of the situation, but yeah, we’re looking at this very closely,” he said. “We’re doing everything that we can to keep our people safe.”

Police in Washington DC, New York and other major American cities said they had increased their presence outside places of worship on Sunday following the US air strikes on Iran.