The political instability that has cursed the UK over the last decade has had one constant: governments have supported Ukraine in its struggle against conquest by Russia. Conservative and Labour administrations alike, and the succession of prime ministers of both parties, have made it clear that the UK stands with Ukraine.

Andy Burnham’s visit to Kyiv makes it absolutely clear that this is one policy that is not set to change under his leadership.

The timing of Burnham’s visit is hugely significant. Ukraine is marking the 35th anniversary of its declaration of independence from the Soviet Union – something Vladimir Putin has never been able to let go, and a central reason he started his war.

Burnham will bring not just a message of symbolic support, but an announcement of even greater military co-operation. The UK’s support for Ukraine has already singled it out for criticism and threats from the Kremlin. Angry words have also rung out from Kensington Palace Gardens, the impressive west London street that is home to the Russian embassy to the UK.

The statement issued from behind the embassy’s imposing walls, and posted on Telegram on 17 August, stretched the limits of diplomatic discourse when it accused “the United Kingdom of acting as an accomplice and co-perpetrator of bloody crimes and terrorist attacks” – that latter phrase being how Moscow sees Ukraine’s decision to take up arms, rather than agree to sign up to Putin’s plans for a new Russian empire.

The embassy warned: “London’s actions will inevitably carry consequences.”

Without waiting to see what those might be, the Prime Minister’s visit offers a defiant response. It coincides with the Government’s announcement that defence firm MBDA “can release classified information on UK components for the long-range missile, Scalp, to establish local assembly lines in Ukraine”.

The British-French Scalp missile, also known as Storm Shadow, has already been used by Ukraine but the move by the UK will allow Kyiv to produce the missiles domestically.

It was Putin’s rage at reports that Ukraine had used British drones in attacks on targets deep inside Russia that prompted the embassy’s menacing Telegram post. So the news that the UK is now to further assist Ukraine’s strategy of bringing the war to the Russian home front can only provoke further fury in Moscow.

Ukrainian strikes on oil infrastructure have disrupted petrol supplies for Russian motorists, and threatened the part of the Russian economy – energy exports – that has helped to fund the Kremlin’s war machine.

Damage to warehouses belonging to “Russia’s Amazon” – the country’s main online retailer, Wildberries – has reminded citizens preparing to vote in next month’s parliamentary elections that the war (or “special military operation”, as Kremlin propagandists typically call it) is not something that is just happening far away.

So how could Russia respond?

The Russian foreign minister, Sergei Lavrov, told the Russian TV programme Moscow. Kremlin. Putin (yes, that’s really what it’s called) on Sunday, the eve of the Prime Minister’s visit to Kyiv: “I feel sorry for Britain if it intends to stand with Ukraine to the very end. President Vladimir Putin has warned them that we have the right to act anywhere across the world’s oceans if someone infringes on our interests or threatens our property.”

Russia’s response could include attempts to target British troops overseas. Were Russia to feel bold enough to strike at a Nato country, British troops in the Baltics could even be a target.

This is in addition to ongoing sabotage against Britain including arson, damage to undersea cables and cyber attacks. An incident in the English Channel in June, in which a Russian warship fired warning shots at a yacht it felt came too close, shows there could be confrontation at sea.

And diplomatic relations are clearly about to get worse. Reports that the Russian ambassador, Andrei Kelin, left his post in July and has not yet been replaced show how damaged ties between London and Moscow are.

Kelin’s experience in the Russian diplomatic service mimics the decline of Britain’s post-Cold war co-operation with Russia. A note in the National Archives, which I uncovered during my recent research into the history of Russia’s relations with the West, names him as a guest at a lunch in Brussels in 1993. British diplomats had invited Kelin and a colleague. At the end, the Russian diplomats made it clear they could not afford to return the hospitality – the Russian embassy was broke.

The sense of humiliation Russia suffered then has since grown into a desire to not only be respected, but feared. You have only to look at the harsh words Putin has had for Nato and the West over the last two decades – especially over policy in the 90s, when Russia was weak – to see how this has been used to justify armed aggression.

Probably still smarting from the fact he had to scale back his own big annual celebration – the 9 May commemoration of the Soviet victory over Nazi Germany – because of security fears, Putin will now be planning how to exercise his self-declared “right to act” – and hit back with a vengeance.