Former US ambassador to the United Nations, John Bolton, has told BBC News that US troops could be used to secure nuclear sites in Iran.

“I could certainly imagine, at an appropriate time, putting American forces on the ground to secure the nuclear sites at Natanz and Isfahan and Fordow and perhaps a few others, to prevent the materials there from falling into the wrong hands,” he said.

“I think that would be a prudent use of American boots on the ground.“

US President Donald Trump has not ruled out sending ground forces into Iran.

Bolton said he found it “hard to imagine there is anything worse than the present government” in Iran, noting the tens of thousands of people killed for protesting against the regime. He said that while doing what they could to facilitate changeover “to a more appropriate kind of government would be in America’s interest as well”, it was not the US’ responsibility to bring about regime change.

“I don’t think American citizens need to be tethered goats to a regime run by a bunch of autocratic, theological extremists seeking to possess nuclear weapons,” the former US national security advisor said.

“I think we are entitled to protect our people, and that of our allies who want to be protected, by eliminating the threat before it becomes real.”

An Iranian flag is planted in the rubble of a police station in Tehran.An Iranian flag is planted in the rubble of a police station in Tehran.Getty Images