A Three-year War and Four Lessons for Europe

The tragic third anniversary of the Russian invasion of Ukraine that began on 24 February 2022 witnesses the start of diplomatic talks between Russia and the United States on the possible end of the conflict. Three years of large-scale, high-intensity war of attrition in Europe, with over a million dead or injured soldiers, offers at least four politico-military lessons for European countries, the EU and NATO. Lessons to bear in mind through this negotiation for the future not only of Ukraine but of the security of the whole continent.

Russia is willing and able to bear the enormous costs of a war of invasion…

The first lesson is that the Russian regime has been able to bear the political, military and economic cost of an unprovoked war of invasion beyond national borders for three years. Over half a million Russian soldiers killed or wounded on Ukrainian soil, almost a million citizens who fled abroad to avoid conscription, the huge military losses – from half of the Black Sea fleet to hundreds of destroyed tanks –, as well as inflation and economic disruptions caused by Western sanctions, have not significantly weakened Putin’s leadership. Sure, there was an attempted mutiny by the Wagner mercenary company in 2023, nevertheless the rebels were eliminated without too many problems for the Kremlin.

In the third decade of the 21st century, Russia is prepared to bear an enormous toll by Western standards, for three consecutive years, just to occupy a few hundred square kilometres in a neighbouring country. This is what greatly worries a large part of Europe, from Scandinavia to the Baltics, from the UK to Poland, as well as the chiefs of the EU and NATO. Especially considering that the Baltic republics had already been occupied for half a century by the Soviet Union and that the long-term goal of the current Russian leadership is to dismantle a Euro-Atlantic bloc that it views as hostile.

…and Ukraine even more so to save 80 per cent of its country

The second lesson is that the Russian armed forces can be halted, at a very high price. It is worth remembering that three years ago, about 200,000 Russian troops invaded Ukraine from the north, east and south to occupy Kyiv, Kharkiv and Kherson – that is, to decapitate the Ukrainian state and take over 100 per cent of its territory. Russia had already occupied about 7 per cent of Ukraine since 2014, when it annexed Crimea and took control of Donbas. In 2022, Moscow expected a military victory in a few weeks, as did many observers in Italy who were deluded or in bad faith – but they were wrong.

Russian forces were pushed back from Kyiv, Kharkiv and Kherson, and – despite offensives and counteroffensives – the front line has set so that Russia now controls just over a fifth of Ukrainian territory.[1] The dramatic, heroic Ukrainian resistance served to save almost 80 per cent of the country from foreign occupation, as well as the destruction, deportations and mass violence that followed. To achieve this result, Ukrainian democracy chose to fight, sustaining both military losses comparable to those of Russia, and civilian casualties due to indiscriminate Russian bombing of Ukrainian cities, at an impressive level by Western standards.

The lesson learned by NATO in these three years is to prepare urgently and for the long term to deter Russia from an attack on a member state and, if deterrence fails to stop it on the border, to push it back by fighting. Indeed, already in 2014, after the first Russian invasion of Ukraine, the NATO members agreed the goal of reaching 2 per cent of GDP invested in their respective armed forces in ten years, which led as many as 21 European states – including all the large ones except Italy and Spain – to exceed this threshold in 2024.[2] Still, Russia’s annual defence spending is higher than that of European NATO allies altogether.

The Atlantic Alliance is also implementing a New Force Model based, among other things, on 100,000 troops available in up to one month and regional plans for reinforcement,[3] and is enhancing the forward deployment of military forces in frontline European allies from the Baltic republics to Bulgaria, exactly to increase the costs and risks of potential attacks from Moscow, thus deterring them.

The readiness of the European armed forces and defence industry is key…

The third lesson is that in such a large, prolonged and complex conflict, the relative advantage given by a single technology or weapon system, be it drones or hypersonic missiles, affects to a certain extent the balance on the battleground but does not change the outcome of the war. Even well-conducted manoeuvres such as the Ukrainian ones to liberate the area of Kharkiv and the city of Kherson in 2022, or to occupy part of the Russian province of Kursk in 2024, certainly helped Ukraine but have not been enough to end the conflict. The sum of the qualities and quantities of the armed forces, in all their aspects and the five operational domains – land, naval, air, cyber and space[4] – is a key factor in a conventional conflict of this kind – until it does not escalate to the nuclear level. Just as is the industrial capacity to supply armed forces with vehicles, weapon systems and ammunition well beyond the stocks available at the beginning of the war and over its first months.

The lesson that Europe is trying to draw from all this concerns both the readiness of its armed forces and, to a certain extent, of European societies – as underlined by the EU report of former Finnish Prime Minister Sauli Niinistö[5] – as well as that of the defence industry to withstand a large-scale and prolonged war. This is where the EU industrial policy initiatives of recent years come from,[6] including the European Defence Industrial Strategy (EDIS)[7] of 2024 and the related investment programme currently being negotiated in Brussels.

…as has been (so far) US support

The fourth lesson concerns US military support to Kyiv. In recent weeks, peace talks have begun not because Russian or Ukrainian forces have won on the battlefield, but because the Trump administration has unfortunately decided to abandon Ukraine to Russia – as was partly predictable already last autumn.[8] Kyiv has been able to defend itself from the Russian invasion for three years also thanks to the military support provided by Western allies for a total value of about 130 billion euros, half of which from the US,[9] and the related support in terms of logistics, training and intelligence.

As the Trump administration drastically cuts this support to force Ukraine to accept a peace favourable to Russia, possibly starting with the concession of its territories occupied by Moscow, either Europe makes a qualitative leap in supporting Kyiv, in terms of military aid and/or armed forces deployed on Ukrainian soil, or the invaded country cannot help but eventually accept the terms agreed between the US and the invader.

Despite attempts at coordination within NATO and the EU, as well as in small ad-hoc groups that met in recent months in Paris, Berlin and Warsaw, Europe does not seem able to influence negotiations conducted bilaterally by the US and Russia at the expense of Ukraine. There is little political support, as well as a number of military difficulties and challenges, with regard to the possible deployment of European troops in Ukraine without the kind of US “backup” asked by NATO Secretary General Mark Rutte[10] but which the US are unwilling to provide. Beyond tactical skirmishes and declarations, the turning point and acceleration brought about by the Trump administration in just one month since taking office at the White House is evident, impressive, and deserves a novel reflection by Europe.

The US can disengage from Ukraine with a limited and indirect, but still significant, impact on its national interests, starting with the message it sends to China about how long American military support for Taiwan would last if Beijing were to try to retake the Island by force. But for Europe, the impact of a peace favourable to Russia resulting from US disengagement, after three years of conflict, has very direct, broad and long-lasting effects that are worth reflecting upon. Especially in light of the other lessons of the three-year war in Ukraine: that Putin’s Russia is currently prepared to bear enormous and prolonged costs to invade a neighbouring country; that Russian armed forces can be stopped but at a very high price; and that Europe must urgently work on the readiness of its own armed forces and defence industry to deter a Russian attack.

Against this backdrop, NATO remains the best politico-military framework to implement the defence of Europe even with a limited and transactional US commitment, because it includes the United Kingdom – as well as Canada and Norway – and presents both integrated military command and infrastructures that can be filled by European assets and personnel.[11] At the same time, the EU is the best politico-economic framework to achieve a higher degree of European strategic autonomy across the board, from defence industry and key technologies to energy supplies, so to enhance the stability and security of its members amidst an increasingly confrontational and uncertain international security environment.

The bottom line is that Europeans must invest in their own collective defence and security more than in the last three decades – probably up to Cold War levels – and accept tough economic choices. Three generations after World War II, the war in Ukraine and the way it may end in favour of Russia have proven what tremendously worse sacrifices are required once conventional conflict returns to Europe.


Alessandro Marrone is Head of the Defence Programme at the Istituto Affari Internazionali (IAI).

[1] BBC Visual Journalism Team, “Ukraine in Maps: Tracking the War with Russia”, in BBC News, last updated on 25 February 2025, https://www.bbc.com/news/world-europe-60506682.

[2] NATO, Defence Expenditure of NATO Countries (2014-2024), 17 June 2024, https://www.nato.int/cps/en/natohq/news_226465.htm.

[3] John R. Deni, “The New NATO Force Model: Ready for Launch?”, in NDC Outlook, No. 04-2024 (May 2024), https://www.ndc.nato.int/news/news.php?icode=1937.

[4] Alessandro Marrone (ed.), Russia-Ukraine War’s Strategic Implications, Rome, IAI, February 2024, https://www.iai.it/en/node/18118.

[5] Sauli Niinistö, Safer Together. Strengthening Europe’s Civilian and Military Preparedness and Readiness, 30 October 2024, p. 8, https://commission.europa.eu/media/59923_en.

[6] Gaia Ravazzolo and Alessandro Marrone, “EU Defence Industrial Initiatives: A Quantum Leap Is Needed”, in IAI Commentaries, No. 24|79 (December 2024), https://www.iai.it/en/node/19309.

[7] On EDIS and its possible contribution to NATO’s deterrence and defence posture see, among others, Federico Santopinto, EU Defence Industrial Policy and Strategic Autonomy: How to Square the Circle with NATO?, Paris, IRIS, November 2024, https://www.iris-france.org/wp-content/uploads/2024/12/ProgEurope_Nov-2024_EN.pdf.

[8] Alessandro Marrone, “Trump, Ukraine and NATO: Two Crossroads for Europe”, in IAI Commentaries, No. 24|67 (November 2024), https://www.iai.it/en/node/19154.

[9] Pietro Bomprezzi et al., Ukraine Support after 3 Years of War: Aid Remains Low but Steady and There Is a Shift Toward Weapons Procurement, Ukraine Support Tracker report, 14 February 2025, https://www.ifw-kiel.de/publications/news/ukraine-support-after-3-years-of-war-aid-flows-remain-low-but-steady-shift-towards-weapons-procurement.

[10] Christian Edwards et al., “Barred from US-Russia Talks on Ukraine, Europe Scrambles for Response with Paris Summit”, in CNN, 17 February 2025, https://edition.cnn.com/2025/02/17/europe/europe-ukraine-summit-paris-trump-intl-hnk/index.html.

[11] Alessandro Marrone, “A Europe-led NATO to Guarantee European Security: The Time Has Come”, in Aspenia Online, 16 June 2024, https://aspeniaonline.it/?p=54692.