Putin threat to go nuclear in Ukraine may not be a bluff, says US

President Putin may not be bluffing with his threats to use nuclear weapons in Ukraine, the American defence secretary said yesterday.

Lloyd Austin spoke after it emerged that US officials have been war-gaming possible responses to a Russian nuclear escalation in the seven-month conflict.

Putin was accused last week of “nuclear sabre-rattling” after he threatened to use Russia’s nuclear arsenal to protect Ukrainian territory annexed after illegitimate referendums.

“There are no checks on Mr Putin,” Austin told CNN. “He made the irresponsible decision to invade Ukraine, he could make another decision.”

The White House has been examining responses including cutting Russia off from the world economy. A military response has been looked at, according to The New York Times, but it would probably be