Andy Burnham has chosen to stand up to Vladimir Putin. And Putin is already plotting his revenge.

'The chatter we've been picking up over the past two weeks indicates the Russians are preparing for something,' a senior security source revealed to me. 'They're planning some sort of action against UK interests. They're going to test Burnham.'

On Monday, the Prime Minister arrived in Ukraine – and he came bearing gifts. After appeals from Volodymyr Zelensky, Burnham agreed to hand over the technical blueprints for Britain's long-range Storm Shadow missiles.

'Ukraine has been Europe's protector: not a drain on our security but the frontline in keeping Europe safe,' Burnham declared. 'The Ukrainian people deserve not just our continued support, but our gratitude and respect.'

But as he spoke those words Andy Burnham knew that frontline is likely to move closer to home. On Sunday, it was announced Russia had withdrawn its British ambassador, without appointing a replacement.

Within the British security establishment this is viewed as a clear indication of an impending Russian intervention. 'We think he's been pulled so that when they act we don't have the ability to expel him,' one source revealed.

My understanding is that while there is as yet no specific intelligence on the precise nature of the possible impending Russian attack, the Prime Minister has been briefed on a number of likely scenarios.

At the top of the risk register is some form of cyber-attack against the nation's infrastructure, possibly aimed at the health service or transport system. 'That would be in keeping with the Russians' MO,' one security source said.

A second area of concern is some form of direct sabotage or attack on Britain's military supply chain. Yesterday Andrei Fedorov, a Kremlin adviser and former deputy foreign minister, warned British factories could be targeted by 'unknown sources'.

Burnham has also been warned there is potential for some sort of clash involving Russian and British military forces. In May, the Ministry of Defence reported that Russian jets had 'repeatedly and dangerously' intercepted a British Boeing RC135 'Rivet Joint' surveillance aircraft.

Last month, a Russian frigate conducted a 'live-fire exercise' off the coast of Plymouth. And in May it emerged an RAF jet carrying then-Defence Secretary John Healey had its navigation system jammed by Russia. As one defence source explained: 'The fear is they will engineer some form of 'incident'. It could be done deliberately. Or the fact the Kremlin is adopting a much more openly aggressive posture towards us could lead to someone down the chain of command precipitating something on their own.'

What is also particularly concerning the security services is the possibility of a direct provocation from the Russians towards the PM himself.

Last year, a house and car previously owned by Keir Starmer were subject to firebomb attacks. It's believed these were initiated by criminals connected to the Russian state. And although two of the perpetrators were ultimately convicted, the assessment is Moscow was pleased with the results.

As an intelligence source explained to me: 'The problem was that after those attacks Keir Starmer came out and said how shaken he and his family had been by the incident. So in the eyes of Russian intelligence that was a successful operation. And that in turn holds out the prospect they will try something similar again.'

Part of the Russian rationale for an attack on the UK would be to directly challenge Burnham's resolve. The Prime Minister is regarded as a blank page when it comes to foreign affairs – and there is an incentive for Moscow to test him.

But there is also a broader perception within Russia, dating back to Boris Johnson, that Britain is a major obstacle to Putin realising his military aims in the region. 'The Kremlin thinks we're standing in the way of victory,' one foreign office source told me. 'Every time they meet with the Americans they're telling them: 'It's the British who are the problem here. There won't be any solution unless you pull the British into line.'

And there is a final reason Putin is now contemplating some form of direct action against the UK. His mounting desperation. Ukrainian 'deep-strike' operations within Russia have turned the war into a political crisis that directly threatens the Russian dictator.

'If you live in Moscow, you can't ignore the war any more,' another intelligence source claimed. 'When you walk out of your house to go to work in the morning you see a giant plume of black smoke from the latest Ukrainian attack. You can't buy petrol. The war's now on Putin's doorstep. And his attitude is: 'The people who are doing this need to get some payback on their own doorstep.'

Since he entered Downing Street the PM has focused on domestic issues. But on Monday, his decision to stand with the Ukrainian people represented a welcome foray on to the world stage. Now we must expect a response to this expression of solidarity. A few years ago another Labour leader – Ed Miliband – was mocked for responding, 'Hell, yeah!' when he was asked: 'Are you tough enough to stand up to Vladimir Putin?'

Andy Burnham has suggested that he is. Putin is now about to put that to the test.