“WHAT is to be done?”, the question Lenin asked 120 years ago, arguing for a political movement that would reshape Russia and Europe for almost a century, is now the one to be answered by every country after Vladimir Putin’s invasion of Ukraine.

An unhelpful, but obviously true, answer is that we should have done something in 2014, when Russia illegally annexed Crimea; especially since the UK and the US were, under the Budapest Memorandum drawn up when Ukraine relinquished its nuclear arsenal, supposed to be guarantors of the country’s security. And that we should have done more by now to tackle the flow of tainted Russian money through Western centres, particularly London; to challenge Vladimir Putin’s appalling human rights record and readiness to commit blatant, even public, murders – including British citizens on UK soil – to achieve his ends; and to avoid becoming dependent on Russian energy.

But we must deal with where we now are. It is no exaggeration to say that is on the brink of potentially the most serious conflict in Europe since the Second World War. Without downplaying previous Soviet attacks – on Hungary, Czechoslovakia and Afghanistan – or the dreadful internecine wars in the Balkans, this is the unprovoked invasion of a huge, stable, democratic sovereign state, bordering EU and Nato countries.

If Ukraine, as so far seems the case, intends and is capable of resisting fiercely, this could be a major protracted war. Mr Putin’s bellicose announcement that anyone who “stands in our way” will face “consequences you have never encountered” amounts to a nuclear threat to western nations, including those, such as the Baltic states and Finland, with good reason to remember and fear Russian incursions.

The West has united in condemnation, and made the appropriate noises, but our actions have not been anywhere near enough. Even a few days ago, the argument for holding some sanctions and measures in reserve could still be made; it is clear that there is little point in that now. What more need Mr Putin do to demonstrate his malign intent and untrustworthiness?

The UK has at least recognised that listing five banks and three individuals is insufficient, and extended its scope. It is right that we are providing military and humanitarian aid, but we need to do everything short of committing troops to full-scale war. We should freeze, or seize, the assets of any business or individual with ties to Mr Putin’s regime, dismiss Russian diplomats, and push for a concerted Western slew of sanctions.

The importance of barring Russia from Swift, the global bank payment system, may have been over-stated, but it would have been a start – Russia’s foreign reserves are not inexhaustible. More important, it would have shown a united front, so it was disappointing to see Germany, Hungary and Italy block that option.

It would certainly have disrupted their energy supplies and economies, but economic measures will do that for every country – sanctions always hurt those imposing them as well as their targets. This will have a material cost, and not an insignificant one, for all of us – Scotland exported nearly quarter of a billion pounds' worth of goods and services to Russia in 2019 – but it is crucial.

Cutting off the Russian political elites from western schools and universities, and homes and assets held here may have a real effect. We should bear in mind, however, that some Russians are expats precisely because of their criticism of Mr Putin, and that he has considerable opposition at home – shown by the incredible bravery of anti-war protestors in St Petersburg, Moscow and elsewhere.

But it is vital that the rest of the world puts up a united opposition to this blatant and vicious act of aggression, for which there is not a shred of justification. Mr Putin’s ludicrous allegations that Nato expansion eastwards would be an act of war were baseless, but he may, perversely, have strengthened the likelihood of an increased presence on the borders of Belarus, Ukraine and Russia, and its appeal to nations with good reason to fear unprovoked attack from a bloodthirsty and utterly unprincipled despot.