Boris Johnson said Vladimir Putin had claimed he could have sent a missile to Britain within a minute in a call just before the invasion of Ukraine.
The former prime minister s comments came in a three-part documentary for BBC Two about the conflict in Ukraine and the lead up to Russia's invasion in February last year.
It had been in a conversation about hypothetical support for Nato on Russia's borders if Putin decided to invade, as Johnson tried to talk Putin down.
He told the makers of Putin vs. the West that he didn't regard Putin's comments as a threat. He went on to become one of the biggest supporters of Ukrainian president Volodymyr Zelenskiy and has visited Kyiv since resigning as prime minister.
The show will air on Monday at 9 pm on BBC Two.
He threatened me at one point and said, Boris, I don t want to hurt you, but with a missile, it would take only a minute or something like that, Johnson said.
I think from the relaxed tone he was taking, the sort of air of detachment that he seemed to have, he was just playing along with my attempts to get him to negotiate. Johnson had warned that there would be tougher western sanctions if Russia invaded, and that support for Nato would increase even if Ukraine was not close to becoming a member.
He said, Boris, that Ukraine is not going to join Nato anytime soon. I said, Well, it is not going to join Nato for the foreseeable future. Johnson said he had a conversation with Putin, and you know that perfectly.
Ben Wallace, the defence secretary, spoke in the documentary about a visit to Moscow in February in an attempt to negotiate and see off war. He met his Russian counterpart, Sergei Shoigu, as well as the chief of the general staff, Valery Gerasimov.
I remember saying to Minister Shoigu, They will fight and he said, My mother is Ukrainian, they won't! Wallace said he had no intention of invading.
That would be vran e in the Russian language. I think Vran e is a demonstration of bullying or strength: I'm going to lie to you. I know you are lying, but I'm still lying to you. He knew I knew and I knew he knew. I think it was about saying I m powerful.
It was the somewhat chilling but direct lie of what they were not going to do, that I think to me confirmed that they were going to do it. I remember as we were walking out General Gerasimov said, Never again will we be humiliated. We used to be the fourth army in the world, now we are number two.