If Nato’s leaders are to draw any lesson from Ukraine’s bitter two-year-long conflict, it is that the alliance remains woefully ill-prepared to deal with the existential threat Moscow poses to its future security.

The military aid Ukraine received from the US and Britain in the early stages of the war undoubtedly contributed to Kyiv’s success in withstanding the initial part of Russia’s “special military operation”, as Vladimir Putin’s invasion in February 2022 was euphemistically termed. The provision of the British Army’s NLAW anti-tank missiles proved particularly effective in helping to thwart the Russian advance on the Ukrainian capital, where Putin aimed to assassinate President Zelensky and establish a pro-Moscow puppet regime in his place.

Nato’s support, especially the supply of long-range missiles, also helped the Ukrainians to achieve several high-profile victories, such as recapturing the strategically important cities of Kharkiv and Kherson towards the end of 2022. Since then, however, a combination of Western dithering, especially on the part of the Biden administration, over responding to Kyiv’s pleas for more weaponry, and Russia’s ability to establish robust defences, including sophisticated electronic warfare systems, has reduced the conflict to stalemate.

The dire predicament Ukraine now faces was reflected in its decision at the weekend to withdraw its forces from the bitterly-contested city of Avdiivka in the Donetsk region, citing severe ammunition shortages. The loss of Avdiivka, which had served as an important stronghold for Ukrainian forces since Russia initially invaded eastern Ukraine in 2014, is a particularly bitter blow. Ukrainian commanders have warned for months that acute shortages of weaponry, especially the long-range artillery vital to thwarting Russian advances, were seriously undermining their ability to defend the 620-mile long front line.

Ukraine’s weapons crisis is partly the result of the political paralysis in Washington over maintaining support for Kyiv, with an isolationist body of Republicans blocking the Biden administration’s efforts to authorise a new $60 billion aid package. But another key factor is the inability of Ukraine’s allies in Europe – including Britain – to sustain weapons supplies at the same level as at the start of the conflict.

British efforts to provide 155mm artillery shells to Ukraine, the most sought-after munitions in the conflict, have been hampered by production issues, with defence manufacturers struggling to make up the shortfall after Britain delivered more than 300,000 of the shells. Years of defence cuts had led to dwindling resupply orders for weaponry, requiring key arms manufacturers to scale down their production lines. Industry experts estimate it could take several years to rebuild UK production to the level needed to sustain a major conflict in Europe against an aggressor like Russia.

The gaps in British arms manufacturing are replicated throughout Europe, where the EU recently admitted that it will not be able to fulfil its pledge to provide Ukraine with 1 million artillery shells by March, owing to a lack of production capacity. By contrast, Russia, where defence spending has now reached an estimated 7.5 per cent of GDP, has enjoyed a major increase in weapons production during the past two years, after Putin ordered industrial leaders to concentrate their efforts on bolstering Russia’s war effort.

Nor is it just in this field that Europe appears singularly ill-prepared to counter any new threat to its security Russia might pose in the coming years.

Another key Ukrainian military requirement – dating back to 2022 – is to be equipped with advanced Western warplanes, such as US F-16s, and more long-range missiles, which will give them the ability to disrupt Russian forces long before they can threaten Ukraine’s frontline defences. Yet, despite numerous offers of advanced pilot training and pledges of around 60 F-16s for Ukraine, the latest Pentagon assessment is that Ukrainian pilots are unlikely to fly F-16 combat missions against Russian targets until at least the end of the year.

Similar delays have hindered the Biden administration’s plans to provide Kyiv with powerful new long-range ATACMS (Army Tactical Missile Systems), which would seriously enhance Ukraine’s ability to defend its forces.

At this rate, and given Moscow’s recent advances on the battlefield, the war could be concluded in Russia’s favour long before this vital Western weaponry sees action, a prospect that should fill European leaders with alarm.

For all their talk of confronting Russian aggression, Ukraine’s faltering military campaign not only serves as an indictment of Europe’s lack of preparedness to address the threat Moscow poses. It will lend Putin encouragement that, as he anticipated when he first decided to invade Ukraine, the West has little appetite for a fight with Russia.

It is essential, therefore, that if a deadly escalation of conflict in Europe is to be avoided, the West redoubles its efforts to provide Kyiv with the weaponry it requires to prevail on the battlefield. Ukraine, after all, is not fighting this war just for its own survival. It is fighting to defend the entire Western alliance.