“Never engage in a pissing match with a skunk: He possesses important natural advantages,” wrote Bryan Cartledge, Britain’s Ambassador to Moscow in the 1980s.

It was the height of the Cold War and Britain had just expelled 25 Soviet spies.

Thirty years on, Britain and Russia are matched-off again.

This time 23 Russian officials have been given one week to leave the UK after the attempted assassination of former spy, Sergei Spiral.

Theresa May said it was 'tragic' that Russia and Vladimir Putin had chosen to act in this way. Picture: AAP (AAP)

The announcement came in a Westminster address.

“To those who seek to do us are harm, you are not welcome here” thundered the Prime Minister.

It was the second time in three days that Theresa May targeted Russia from the floor of the British Parliament.

But on this occasion, she wasn’t just talking the talk.

Vladimir Putin has yet to officially respond to Theresa May's accusations. Picture: AAP (AAP)

The PM had promised “extensive action” should Russia fail to explain its involvement in the poison attack on Skripal and his daughter, Yulia.

After Russia ignored the ultimatum, Mrs May announced the biggest diplomatic expulsion in 30 years.

It’s suspected that these individuals are “undeclared intelligence officers”.

Within minutes, news crews were camped outside the Russian embassy near Notting Hill waiting for any sign of movement.

But Mrs May wasn’t finished:

The PM confirmed that Ministers and Royal Family Members would be boycotting the Russia 2018 World Cup.

Former spy Sergie Skripal, left, was with his daughter, when poisoned. She is also fighting for life. Their last movements were caught on CCTV.

A British invitation to the Russian Foreign Minister was cancelled.

High-level contacts between the United Kingdom and the Russian Federation were suspended completely and new laws were flagged to give Britain greater sanction powers.

There will also be greater scrutiny on private planes and cargo coming into the UK.

Ten days after the attack, the Skripals cling to life in hospital.

The former spy and his daughter were poisoned after eating out in the UK town of Salisbury.

Tests have proven that the poison used was a Russian-developed, military-grade, nerve agent known as Novichok.

UK citizen Sergei Skripal was poisoned in Salisbury 10 days ago and is still fighting for life. Picture: AAP (AAP)

It has also emerged that Mr Skripal was a UK citizen.

“This was not just an act of attempted murder in Salisbury,” said Mrs May.

“It is an affront to the prohibition on the use of chemical weapons”.

Some argue that the “skunk” thesis does not apply in 2018.

Defence expert, Robert Fox, from London’s King College says May was right to talk tough Russia.

“Vladimir Putin’s posture is based on belligerent rhetoric and deception — saying one thing and doing another,” Fox told The Evening Standard.

“Now is not the time to give in to Putin’s bluster. It may be time diplomatically to call his bluff”.

President Putin is yet to respond.

But the Russian Embassy has called the expulsion “unjustified” and “short-sighted”.

The Russians go to the polls on Sunday. Putin is the favourite at extremely short odds.

On the streets of Moscow, loyal locals are not impressed.

“I think Russia is behaving fairly. I think the conflict will develop," said Olga Bykova.

The expulsion are part of an escalating crisis.

When Putin critic, Alexander Litvinenko, was assassinated in London in 2006, Putin was again the main suspect.

That time Britain expelled just four Russian diplomats.

This time it is a much bigger deal.

Cold War Author, Calder Walton, points out that the expulsion of 23 diplomats represents more than 40% of the Russian delegation in London.

The Times of London editorialised that the Skripal incident forms part of “most serious threat to western democracies since the Cold War”.

They argue that Russia is becoming increasingly aggressive towards western powers that they read as “weak”.

According to The Times there is only one clear response to the increasing aggression.

Ordinary citizens of west - which would include Australians - “must rally to the defence of democracy”.

It’s difficult to say where the situation will go next, but Mrs May is not backing down.

“We wanted a better relationship. it is tragic that Mr Putin has chosen to act in this way,” the PM told the House of Commons.

If this is a Cold War-style “pissing contest”, it’s showing no signs of trickling out.