Iran threatened to activate terror sleeper cells inside the United States if the country attacked, reports suggest.

Axar.az informs. citing Telegraph, sources told NBC News that Iran sent a communiqué to Donald Trump in the days before the US’s strikes, threatening to green-light the terror sleeper cells.

Mr Trump received the message via an intermediary at the G7 summit in Canada last week. He later told reporters he was not “in the mood” to negotiate with Iran.

Sleeper cells are essentially spies or terrorists who operate in the US and remain inactive until they are ordered to act.

It comes as Mr Trump authorised strikes on Iran’s three nuclear bases, Fordow, Natanz and Isfahan, on Saturday night in a stealth mission he hailed “a spectacular military success”.

The US president had previously vetoed an Israeli plan to kill Iran’s supreme leader, Ayatollah Ali Khamenei, according to American officials.

Israeli officials said they believed Iran’s heavily-fortified nuclear site at Fordow sustained serious damage from the strikes but had not been completely destroyed. A US official told the New York Times it had been taken “off the table”.

On Sunday, Benjamin Netanyahu, the Israeli prime minister, claimed Israel was “close” to wiping out Iran’s nuclear capabilities and ballistic missiles.