THE sirens in Kyiv have sounded and its citizens are fleeing for their lives after Vladimir Putin fatefully decided to open a Pandora’s Box in Ukraine.

While we don’t know the full consequences of the Russian President’s act of war, it marks the beginning of another dark chapter in Europe’s bloody history.

Yet the signs of Russian aggression have been there for some time with the 2008 invasion by Russian “peacekeepers” of the Georgian territories of South Ossetia and Abkhazia and six years later with the annexation of Crimea to the Russian Federation.

And now, Putin having repeatedly insisted Russia had no plans to invade Ukraine, it has done so.

After the West imposed sanctions following the invasion of Crimea, Moscow began to build up Russian defences, reducing heavily its foreign exchange reliance on the US dollar.

Last month, the country’s gold and foreign currency reserves hit a record high of £464bn, which could be used to shore up the rouble in the months ahead.

Its drive for self-reliance has meant Russia has become less dependent on foreign loans and investments while focusing on new non-Western trade opportunities.

And the Russian President’s rhetoric has been ramped up to justify to the Russian people his aggression.

On Monday, in a rambling televised appearance, Putin suggested Ukraine had become “a colony with a puppet regime” and was not really an independent state.

He also falsely claimed Kyiv wanted its own nuclear arsenal and argued the Ukrainian government was not acting “in the interests of its people”. In 1991, 92% voted for independence from the ex-Soviet Union. Today, more than 60% want to join Nato and the EU.

Yesterday as the invasion began, Putin branded the West the “evil empire,” claimed Ukraine was being run by neo-Nazis and his military action was to “deNazify” the country.

In the thinnest veiled threat, the Russian dictator suggested if the West sought to stop the invasion, it would lead to “consequences they have never seen” ie a nuclear war.

Putin insisted only military assets were being targeted and Russia did not intend to occupy Ukraine, claiming responsibility for the bloodshed lay not with Moscow but with Kyiv. However, the words of a tyrant are meaningless.

Intelligence reports said there had been more than 80 strikes at Ukrainian targets with ground forces advancing across the border from at least three points; Donbas, Crimea and Belarus.

Following Russia’s invasion, stock markets across the globe slumped and oil prices soared to levels not seen in eight years as a result of the crisis.

The effect on Britons will be higher petrol prices and higher food costs. Analysts, having predicted inflation would hit 7% later this year, now fear it could top 8%. Russia and Ukraine export a quarter of the world’s wheat.

In a week of worrying comments, some of the starkest came from Sajid Javid, England’s Health Secretary, who said the situation was on a par with the 1962 Cuban missile crisis, when the world teetered on the brink of nuclear war.

“I would agree with that analysis…I do think it’s as serious a situation as that. We are waking up to a very dark day across Europe,” he added.

Yet what Putin fears most is a threat to his Tsar-like rule from a swath of freedom-loving liberal democracies on Russian’s doorstep, which could become more attractive, particularly to young Russian minds.

It seems clear the Russian people do not want a European war; this is a conflict made in the Kremlin, engineered by Putin and his gang of oligarchs.

His strategy is predicated on how the West will rage against Russian aggression, initiate sanctions but after a few months it will be business as usual. After all, that is what happened after Russia invaded Georgia and Crimea with dodgy Russia money flowing happily through the City of London.

Yet rather than weakening the Nato alliance Putin has strengthened it and made his country a pariah state.

As hundreds of protesters demonstrated outside Downing St, calling for the “total isolation of Russia,” politicians up and down the land denounced Russia.

At Holyrood, Nicola Sturgeon denounced Putin’s “unprovoked, imperialist aggression” and insisted he must “feel the wrath of the democratic world”.

At Westminster, one of the strongest reactions came from Tom Tugendhat, the Conservative chairman of the Commons Foreign Affairs Committee, who called for “all” Russian citizens to be expelled from Britain and “all” Russian assets to be frozen.

After what were dubbed “peashooter” sanctions of earlier this week, Britain and its allies looked to deepen and broaden their counter-measures.

Following a virtual G7 meeting to co-ordinate sanctions with the US and EU, Boris Johnson in a Commons statement branded Putin a “blood-stained aggressor, who believes in imperial conquest…” He denounced the Russian leader’s “squalid venture” and said he was “trying to redraw the map of Europe in blood”.

The PM unveiled a “ferocious package of sanctions,” which included stopping major Russian companies and the state from raising finance or borrowing money on UK markets, freezing the assets of 100 new individuals or entities and banning Aeroflot flights from landing in Britain.

But the biggest stick, cutting Russia out of the international Swift payment system and thus impacting its banks’ ability to operate abroad, was not used. But Johnson told MPs this was being held in reserve as "nothing is off the table".

Given what has happened, the Baltic states are now understandably alarmed, fearing they could be next on Putin’s list to recreate a Soviet-style empire.

But they are Nato members and if one Russian boot steps across any of their borders, then the world would move into a different, far more dangerous dimension.

Today, the West’s watchwords must be unify and isolate.

If Putin is not stopped, then others, notably China, will look to see that aggression pays and the world will become a much more perilous place. As we think of the people of Ukraine, the alliance must show solidarity and, above all, keep its nerve.