Former head of British Army Lord Dannatt says Putin could fire nuclear weapon into sea or desert

• Watch General Lord Dannatt speak to ITV News Anglia's David Whiteley

The former head of the British Army has said Vladimir Putin could fire a nuclear weapon "into the desert somewhere" to show his enemies how serious he is.

General Lord Dannatt, who was General Chief of Staff between 2006 and 2009, described the president's threats as "appalling and unthinkable" but said Mr Putin had already "shown himself not to be as rational as a leader really ought to be".

The Russian leader has ordered nuclear deterrent forces be put on high alert, as tensions with the West mount over his invasion of Ukraine.

Speaking to ITV News Anglia, Lord Dannatt, who served with the British Army for 40 years, described the war in Ukraine as "the most serious set of circumstances that's occurred in the 71 years I've been on this planet".

He added that it was "very difficult" not to take threats of nuclear action seriously but said he did not believe Mr Putin would target a populated area.

"I don't think for a minute he would actually order taking out a city or a conurbation," he said.

"I think he's more likely to use a nuclear weapon in a demonstrative way - fire it into the sea, fire it into the desert - just to show that he's serious. But even that is unthinkable and just shouldn't be happening in the 21st century."

Shortly after ordering the Russian defence minister and the chief of the military’s General Staff to put the nuclear deterrent forces in a “special regime of combat duty”, the Kremlin suggested comments made by UK foreign secretary Liz Truss had led to that decision.

Lord Dannatt, who lives in Norfolk, said South West Norfolk MP Ms Truss had been "talking tough" like many British and European leaders.

But, quoting Theodore Roosevelt on international diplomacy, he said: "'The ideal is to carry a big stick and talk softly.'

"Sadly, the west doesn't have a big stick at the moment. The UK armed forces are much reduced from what they were so our stick isn't very big.

"But conversely, we are talking very loudly. Whether this is a good combination, I think time will tell."

Lord Dannatt said the West had spent many years hoping Mr Putin would not follow through on his threats, such as entering Georgia in 2008, annexing Crimea in 2014, and more recently invading Ukraine after amassing thousands of troops on its borders.

But he praised Ukrainian troops for their spirit, which he said had already taken Russian soldiers by surprise and left many of them "bewildered, dismayed and extremely surprised" by the strength of opposition they had faced.

He said he believed Russia's armed forces had been led to believe they would be welcomed as peacekeepers or liberators when they crossed the Ukrainian border.

"In this era of bare-faced lies, fake news and just straight-forward disinformation, I think these young Russian conscripts are being treated quite appallingly," he said.