Dr Liam Fox is former a Defence and International Trade Secretary. He was the UK’s Nominee to be Director-General of the World Trade Organization (WTO) in 2020.

President Zelinsky made a historic address to the House of Commons by video-link this week. It was part of his campaign to obtain greater support from the free world in his battle against the brutality inflicted by Vladimir Putin’s Russia. He was dignified and moving, reminding Britain about how we too had to defend ourselves in an existential battle, against Nazi Germany.

Quoting Shakespeare and Churchill, he told us that his country had to choose “whether to be or not to be” and most powerfully, to a number of tearing eyes, “we have chosen to be”. He thanked the international community for its support and called for Russia to be declared a terrorist state.

Watching the developing picture of death and destruction in real time on our TVs and on social media has brought the reality of war into our homes in a way that I have never known before, and there is a great, and understandable, emotional response elicited in us all that we must do all we can to help. But we must be careful not to let our hearts, for the best of motives, rule our heads with potentially dire consequences.

An escalation of the military campaign with NATO involvement would not only risk turning the conflict into a full-blown European conflagration, but it would play into Putin’s narrative that this is essentially a Russian war of defence against an aggressive NATO alliance.

Instead, steady nerves and the use of our economic might is the best way to defeat Putin in the long term. We should remember that it was the economic might of the West that was ultimately a key determining factor in the fall of the Soviet Union, alongside our willingness to spend on defence and a staunch belief that our values were worth defending. The latter two need reinforcing today.

It is important to understand the scale of the economic sanctions being imposed on Russia and the catastrophic impact that they could have. Putin has built up a substantial financial war chest since his annexation of Crimea in 2014, no doubt anticipating a high cost for the campaign that I always believed he would try to finish.

Around $630 billion was put aside from sales of oil and gas, largely to Europe. It is held in Euros (32.3 per cent), USD (16.4 per cent), and others holdings include Sterling (16.5 per cent) and Chinese Renminbi (13.1 per cent), with gold at 21.7 per cent.

The five top holders of Russian foreign exchange reserves are, in order, China, France, Japan, Germany and the United States. At a stroke, almost two thirds are difficult to utilise and out of Putin’s grasp. The international cooperation to make this happen is unprecedented and though massively helpful now, may have long term consequences, some of which may not be positive.

The crisis for Russia (which has already seen the Rouble crash and interest rates double) is that the Russian central bank is not only the lender of last resort to its domestic banks in the domestic currency, but also the lender of last resort in foreign exchange.

The reserves thus prop up the value of the currency and ensure the stability of the banking system. People are reported to be taking their money out, not because they fear the availability of their money or the drop in value, but because the banks may not be here next week. A run on the banks, on which Russian businesses and citizens depend, is suddenly a real possibility and the horrifying spectre of hyperinflation for the Russian people has become a potential outcome for their President’s actions.

It is clear that Putin never imagined that the West would have such coherence in its response to his wicked adventurism. Indeed, while he seems to have been prepared from the outset for a full-scale invasion, he might have hoped that the sheer threat of violence and the huge build-up of troops along the borders might have elicited a weak response from both the Ukraine and the international community.

After all, he had invaded Georgia in 2008 with little price to pay, had annexed Crimea in 2014 with little more than a whimper of international response, and had witnessed the humiliating withdrawal from Afghanistan, which would have been read as weakness on behalf of the United States and its allies.

What Putin clearly also had not expected was the poor logistical performance of his own invading forces or the level of resistance from the courageous and patriotic Ukrainians. He certainly will not have expected the scale and breadth of the economic sanctions being applied not only by the usual allies, but also countries such as Switzerland who, in breaking the long-standing tradition of neutrality, have joined the free world in freezing Russian financial assets in a country which has long been a destination for Russian oligarchs’ money.

It all adds up to a picture of a man poorly briefed, unwilling to listen to better counsel or both. It is a classic example of a callous dictator who falls victim to his own unchallenged fantasies and malevolence.

So why not add NATO’s military might into the equation? Why would a no-fly zone be such a bad idea? After all, some say, NATO carried out a no-fly zone in the Balkans war in 1993 (though it is worth noting that this was not a unilateral action by NATO but the enforcement of a UN resolution which prevented the significant use of air power by either side in the conflict). Certainly, a no-fly zone is one of the asks that President Zelensky has been making in his diplomatic mission.

The answer was well put when the Chief of the Defence Staff, Admiral Sir Tony Radakin, who stated: “the advice that we as senior military professionals are giving our politicians is to avoid doing things that are tactically ineffective and definitely to avoid doing things that tactically might lead to miscalculation or escalation”.

He correctly pointed out that most of the destruction we have witnessed in Ukrainian cities has come from Russian artillery rather than aircraft and added that “If we were to police a no-fly zone, it means that we probably have to take out Russian defence systems and we would have NATO aircraft in the air alongside Russian aircraft, and then the potential of shooting them down and then that leads to an escalation”.

The idea of proactively bombing Russian air defence bases in order to make a no-fly zone permissive for NATO aircraft and pilots is not only to create the near-certain of a wider European military escalation but would, once again, play into the Putin narrative that NATO is a threat to Russia.

This is, and must remain, Putin’s war. His claims that Russians were being subjected to bullying and genocide by the Ukrainians and that the “demilitarisation and de-Nazification” of Ukraine, a vibrant European democracy, was necessary are as ridiculous as they are vile. Yet, they fit a pattern. Putin has frequently accused Ukraine of being taken over by extremists since its pro-Russian president, Viktor Yanukovych, was ousted in 2014.

Thankfully, it is difficult to see the Ukrainian invasion ending well for him though it is yet impossible to determine the price that will be paid by others, especially the Ukrainians.

Meantime, although we should arm the Ukrainian forces as best we can, we should not fan the flames of a wider European war but tighten our economic grip in a way never before seen in history. How ironic for Putin if his end is delivered by the force of western capitalism.