On the evidence of the first month of this year’s polling, Donald Trump could beat Joe Biden in the American presidential election in November. There is a long way to go – on the campaign trail and in the courts – but the minds of European leaders are turning to the nightmare question: what happens to Ukraine, and indeed to the North Atlantic Treaty Organization, if Trump becomes president again?

This question haunted Emmanuel Macron, as the French president addressed the Swedish Defence Academy last week. ‘This is a decisive and testing moment for Europe. We must be ready to act to defend and support Ukraine, whatever it takes and whatever America decides’, he said, hinting that the project could strengthen Europe’s autonomy from its transatlantic ally.

The same fear lies behind a joint letter, signed by the German chancellor, Olaf Scholz, and the prime ministers of Estonia, Denmark, the Netherlands and the Czech Republic, calling for a major scale-up of European military aid to Ukraine. ‘If Ukraine loses’, the letter says, ‘the long-term consequences and costs will be much higher for all of us’.

There was relief on Thursday at the unanimous decision by the European Council to raise €50 bn for Ukraine during the next two years — the Hungarian prime minister, Viktor Orbán, having withdrawn his earlier veto under pressure. But the strategic concern remains.

Huge challenges for EU leaders

Even if Trump were re-elected, it’s unlikely that the United States would actually withdraw from NATO, despite his past threats to do so at the organisation’s 2018 Brussels summit. A decision to abrogate the 1949 North Atlantic Treaty would require a vote in Congress and expend political capital Trump may not have. By executive order, he could, however, draw down American personnel from NATO duties in Europe or – following the model of France from 1966 to 2009 – withdraw from the military-command structures of NATO. More particularly, he could pull aid, intelligence support and the supply of ammunition to Ukraine, in an attempt to engineer a sell-out peace deal favouring Russia.

So, European leaders face three huge challenges. They need to find tens of billions of euros to plug a funding gap left by the US. They must ramp up their fragmented and competing arms industries to supply the weapons, ammunition and intelligence needed. And they must do all this while mounting a credible force at NATO’s borders – to deter further Russian aggression – with no guarantee of American backing.

Europe needs a unified defence strategy and the capability to execute it.

Let us be honest. Suppose that they could find the money and that they could scale Europe’s defence industrial capacity to support Ukraine — even that the United Kingdom as a NATO though ex-EU member was fully integrated into the project. The intelligence, surveillance, targeting and reconnaissance tasks now carried out under US leadership would be beyond the European powers as currently equipped.

Whether they committed to the task and failed or – more likely – folded in the face of the enormity of the problem, the implications for Ukraine would be the same. It would be forced to seek a temporary peace with Russia, to avoid being overrun once again in the summer of 2025.

Europe, in short, needs a unified defence strategy and the capability to execute it. Fortunately, the foundations are there on which to build.

Europe is rearming

NATO’s new strategic concept, approved after Russia’s full-scale invasion of Ukraine, outlines the scale and suggests the structure of the conventional armed forces needed. It envisages a capacity to deploy 100 000 troops within 10 days of a crisis under Treaty Article 5 – the mutual-defence clause – with double that number from day 10 to day 30 and half a million thereafter.

American military personnel number 1.4 million, so, with their inclusion, that is feasible. If the US were, however, out of the picture or only ready to commit in the third phase, a lot of pre-installed military force up-front would be required from Europe. With 1.3 million personnel in total, Europe’s armies roughly match that of the US, but they are nowhere near as heavily equipped.

Military planners, from the UK to Estonia, have been making speeches warning Generation Z that the risk of armed conflict in their lifetime is non-negligible.

Poland is investing in 1 000 new Korean-designed tanks and 1 400 new fighting vehicles. It is clearly positioning itself as the lynchpin of forward defence, and it could expect the rearmed and refurbished forces of the German Bundeswehr to fight alongside it. Finland possesses a formidable reserve-based army, while Sweden is ratcheting up the output of its renowned arms industry. Britain, meanwhile, has cut army numbers to their lowest since Napoleon and is still formally committed to the ‘Indo-Pacific tilt’, which emphasises post-imperial maritime power and a presence throughout the Gulf and Far East.

But as they rearm – some enthusiastically, others not – European states are exposing fundamental weaknesses: lack of standardisation, obsession with ‘exquisite’ weapons built to burnish the global reputations of favoured defence companies, lack of capacity to reproduce vehicles and aircraft lost in combat, insecure supply chains and a bevy of ‘national champions’, which needlessly compete with one another.

If we take a second Trump presidency and an unjust peace forced upon Ukraine as the worst-case scenario, another ominous aspect of it could be a rapid Russian rearmament with equipment from China. That is why military planners, from the UK to Estonia, have been making speeches warning Generation Z that the risk of armed conflict in their lifetime is non-negligible.

How and why should we fight?

What is needed is a co-ordinated plan: to scale up rapidly Europe’s defence industrial capacity (and with Britain an enthusiastic player, not a bystander). Through partnerships and standardisation, European states need to solve the problem of generating ‘mass’ on the battlefield — producing cheap, generic, reliable military vehicles, artillery and air-defence systems that can be replaced quickly when destroyed and training reserve troops to use them.

Because such output is regarded as low value by the private-equity and venture-capital groups that populate the ownership structures of the defence industry, states will likely have to direct this effort — even better would be large consortia of states working in partnership. Yet, beyond that, NATO’s European members need to address two questions politicians have barely begun to answer: how shall we fight and why would we?

Few among the current generation of leaders came into politics to focus on national security — as against economic growth or human rights and justice.

As to the first is a truism that armies start wars, but societies and economies win them. Europe has an economy and a civil society capable of successfully deterring aggression. But the US plays the co-ordinating role within NATO, and there is no potential replacement for that. For example, the US army has decreed a return to ‘divisionality’ in its operating concept: basically, the smallest counter on the map of a US general will represent a three-brigade force numbering up to 15 000 soldiers. Most European armies do not operate command structures at a divisional scale but are rapidly adapting to the US change of emphasis. If America becomes an unreliable ally, who will call shots like these is unclear.

The ‘why would we fight?’ question is existential. In the cafes of Helsinki and Tallinn, the answer is a no-brainer, even among Generation Z. They understand very well that their high-technology, liberal cities could be reduced to a hellscape on day one of any Russian attack. It feels very different in the older Western democracies, which have become prime targets for Russian hybrid warfare and disinformation, but where there is no folk memory of the Soviet Union.

Few among the current generation of leaders came into politics to focus on national security — as against economic growth or human rights and justice. Even among the few who understand the scale of the danger, they have parties to steer, budgets to balance and the pacifism of their voting base to manage. So, the threat of a second Trump presidency must focus politicians’ minds. There is a clear mismatch between NATO’s concept – forward deployment of troops to deter Russian aggression – and its ability to deliver. That has to be resolved through partnerships, active industrial strategy and the geopolitical management of supply chains. Above all, it requires alerting voters to the severity of the threat — should a re-emergent Trump deliver Europe a stab in the back.

This is a joint publication by Social Europe and IPS-Journal