The UK and EU are struggling to expand weapons production enough to defend Ukraine and the continent from Russia if Donald Trump becomes US president and withdraws military support, senior former diplomats have warned. 

There is a genuine danger of Mr Trump winning office and reducing American commitments to Nato, causing “the most serious crisis in the alliance’s history”, a former British ambassador to the organisation told i. 

This would be “a geopolitical shock like no other”, said Sir Adam Thomson, who served as the UK’s permanent representative to Nato between 2014 and 2016. 

Nato “can’t do without the US – the Americans really are critical to all the alliance’s big modern needs”, said Sir Adam. 

He believes that over the next year this “will drive accelerated European efforts to compensate” for any sudden defensive shortages, but this will be “very difficult” to achieve in such a short timespan. 

An ex-UK ambassador to Ukraine also told i that if Washington stops backing Kyiv, there is a “serious risk” this could deal a “terminal blow” to the country’s war effort and imperil the rest of Europe. 

If Mr Trump wins the election and “cuts off” support to President Zelensky, “the ability of the Ukrainians to stick with the conflict is under serious threat,” said Simon Smith, who ran the British embassy in Kyiv between 2012 and 2015. 

Mr Smith fears this could encourage the Kremlin leadership to “reheat the much more ambitious territorial plans they had in February 2022, basically to be all over Ukraine. That must be a big worry.” 

Ukraine’s supply crisis 

On the second anniversary of Russia launching a full-scale invasion of its neighbour, both men underlined that Mr Trump’s potential actions if he becomes president in 11 months are hard to predict because of his “short-term” approach to governing.  

But his vocal opposition to supporting Ukraine’s defence is causing huge problems now. Because of Mr Trump’s influence on congressional Republicans, it remains uncertain whether the US will be able to deliver its next $60bn aid package to Kyiv. 

“He’s already impacting European and British security,” said Sir Adam, who is now director of the European Leadership Network think tank. 

“Trump has completely shifted the Republican party’s position… Now it’s in real doubt whether the Republicans will allow any aid from the US to Ukraine.” 

He added: “If the Trump effect means no US aid to Ukraine in 2024, probably enough would be done to prevent a Ukrainian collapse. 

“But we’re already seeing that the US is an unreliable ally on Ukraine. That could mean that Kyiv gets no US money and no US weapons this year.” 

This has frustrated US president Joe Biden. His national security adviser, Jake Sullivan, said last week: “We’ve been increasingly getting reports of Ukrainian troops rationing, or even running out of ammunition on the frontlines.” 

To fully replace US military assistance in 2024, the Kiel Institute for the World Economy said this month that Europe would need to “double its current level and pace of arms assistance”. 

Belgium’s former deputy chief of defence, General Marc Thys, has even said that Europe is in “deep shit” over ammunition production levels. The continent’s industry “isn’t strong enough to support Ukraine,” he told Politico.

“He’s already impacting European and British security”

Sir Adam Thomson

Sir Adam believes that although European leaders would be willing to spend more money on Ukraine to help address any shortfall, actually manufacturing more weaponry will prove tricky no matter how much money is pledged. 

“The political will would be found to back Ukraine militarily to the maximum extent possible. The question is what that maximum extent actually is in 2024, because Europe is failing on its target of 1 million 155mm shells to Ukraine and we’re told that European armament factories are at full stretch.” 

Mr Smith, chair of the Chatham House Ukraine Forum, agrees. “If they really changed gear on defence production and defence expenditures, this is probably a gap the Europeans could fill,” he said. 

“But do you really envisage those resources being brought together? That’s where I’m a little sceptical… The production issue, of how quickly this can be done physically in the time available – that is a problem.” 

“The Russians might well see a gap in provision to Ukraine as an opportunity”, he said. It might encourage them to “dig in” first, then “punch through the lines in one or two places”, before increasing the “scale and purpose of future offensives”.

A Ministry of Defence spokesperson told i: “The continued provision of military support to Ukraine from the international community is essential – which is why the UK has increased the amount we are spending on military aid to £2.5bn for the next financial year, underscoring our long-term commitment to supplying Ukraine with the aid it needs to achieve victory.

“On Thursday, the defence secretary reaffirmed this commitment in Parliament – further announcing a new package of highly effective Brimstone anti-tank missiles.

“Last week he met with international leaders at Nato Headquarters in Brussels and at the Munich Security Conference, to encourage partners and allies to also increase their support.”

“The Russians might well see a gap in provision to Ukraine as an opportunity”

Simon Smith

Dangers for Nato and Europe 

A Russian victory in Ukraine, combined with US isolationism, would leave Europe far more vulnerable to Russian attack, analysts think. Some fear “disaster“.

Mr Smith said: “A Putin who has won the war in Ukraine is not going to go back to Moscow and say: ‘Blimey, I’ve got away with that, enough of that for the time being.’ He will be immensely encouraged to disrupt and destroy further the European structures that have been so painstakingly built since the early 1950s.” 

Sir Adam agrees. “There is plenty of reason to think, from all Putin’s utterances and behaviours, that if Europe looked weak in defence terms, he would seek to take advantage of that – politically, certainly, but potentially also militarily,” he said. 

“We need to be stronger. With Russia, you are damned if you do and damned if you don’t. If you ramp up, they get paranoid and feel threatened. If you don’t, they take advantage.  

“I think he is currently very deterred by Nato, but Trump could do an awful lot of damage to the credibility of that deterrent.” 

He continued: “For the duration of a Trump presidency – four awful years for transatlantic relations – the Europeans would have to show that they could get serious about their own collective defence. 

“In that sense, Ukraine is a blessing in disguise for Nato. The Ukrainians have so dramatically degraded Russia’s ground forces that they probably aren’t a significant military threat to anything else in the short to medium term.” 

However, that could change within as little as five to eight years, he said.

“There is plenty of reason to think, from all Putin’s utterances and behaviours, that if Europe looked weak in defence terms, he would seek to take advantage”

Sir Adam Thomson

Mr Trump says he would encourage Russia “to do whatever the hell they want” to European countries that do not contribute enough to Nato, telling them: “I’m not going to protect you.” The serving US ambassador to the organisation has called his remarks “irrational and dangerous“.

Mr Trump called Nato “obsolete” in 2017. His former national security adviser, John Bolton, says the former president came close to pulling the US out of the alliance altogether at a conference in Brussels in 2018. 

“He’s not negotiating,” Mr Bolton told Politico this month. “His goal here is not to strengthen Nato, it’s to lay the groundwork to get out.”

Congress passed a bill in December preventing presidents from leaving the military alliance without approval from two thirds of the Senate. But even if the US remains a member, a president could reduce contributions and not order his military into action if an ally is attacked.

European members have responded by announcing record military spending of $380bn this year. At least 18 countries, including the UK, will meet their target of dedicating 2 per cent of their GDP to defence, up from just five nations in 2016. 

“We are making real progress,” Nato’s secretary-general Jens Stoltenberg said this month. “European allies are spending more.” He accepted it is “valid point” that the continent should focus more on its own security. 

Last month Nato signed a €1.1bn deal to buy more ammunition which members can use either to restore their depleted reserves or to help Ukraine. 

Mr Smith said: “It makes sense for the UK and Europe to be increasing arms spending and production for our own future defence from Russia, as well as for Ukraine. 

“There is more that the UK could be doing. The British government is probably right to remind people that our record on Ukraine is not at all bad, but there’s a requirement right across Europe.”  

Rishi Sunak, the prime minister, announced a £5bn increase in British defence spending last year. 

Grant Shapps, the defence secretary, argued this month that investment in the UK’s armed forces is “crucial” while “threats increase across the globe”. “That’s why we’re spending more than £50bn annually, helping equip our military with cutting-edge capabilities, so they can continue to protect our freedoms around the clock,” he said. 

But the Ministry of Defence’s 10-year plan for new weapons has a budget “blackhole” of £16.9bn, according to the National Audit Office.

Growing UK diplomatic concerns about Trump

• The latest warnings about Donald Trump follow concerns raised by other leading Foreign Office veterans about the “massive” security risks that he poses to the UK and Europe. 
• Lord Simon McDonald, a former Foreign Office chief, and two ex-ambassadors to the US, Sir Peter Westmacott and Lord John Kerr, told i last month that the British government can afford no complacency given Mr Trump’s poll ratings in the US. This is despite the immense political and legal challenges he must overcome to become president again.

• A serving intelligence source has since confirmed that MI6 has been helping to draft a dossier “listing the impacts to national security at home and abroad” if Mr Trump enters the White House in January 2025. 
• Lord Gavin Barwell, who was chief of staff to Theresa May while she was prime minister, has warned that the UK and its European allies may need “to turn their economies into war economies” if US support is reduced by a Trump presidency. 

Trump’s ‘temperamental and mentality issues’ 

Although Mr Trump has stormed ahead in Republican primaries and leads opinion polls against Mr Biden, it remains far from certain that he will even be on the ballot in November, let alone that he will win. 

He faces four separate criminal cases this year, which could mean he is a convicted criminal by the time of the election, though he denies all charges vociferously. 

It’s also possible that he may be barred from standing for election over his alleged involvement in the attempted “insurrection” at the US Capitol in 2021, which he disputes. 

However, if he overcomes these hurdles, Mr Smith has seen up close the chaos that Mr Trump can cause in world affairs, having served as UK ambassador to South Korea from 2018 to 2022. 

He was working in Seoul while Mr Trump met North Korean dictator Kim Jong-Un, having previously threatened to “totally destroy” the totalitarian state. 

“Rather notoriously, Trump is now on record as saying that he would sort out Ukraine and Russia within 24 hours. To me, that carried a rather disturbing echo of his approach once he became fascinated in the North Korea issue,” he said. 

“He’s too lazy and, I think, actually too stupid to understand complex argument”

Simon Smith

Fundamentally, Mr Trump’s approach amounts to “barging in and taking over and doing it all himself,” said Mr Smith. 

“He’s an impulsive character. He will do whatever looks best for him, in terms of how he looks better tomorrow than he did today. He doesn’t think ahead. 

“One of his worst negative attributes is that he hates being bothered by detail. He’s too lazy and, I think, actually too stupid to understand complex argument, so he tries to simplify everything. His method of simplification is to say: ‘I will deal with it.’” 

These “very serious temperamental and mentality issues” alarm Mr Smith when the US, Ukraine and world need a “carefully structured strategy”.  

On the Russia-Ukraine conflict, he fears that any advantage will be “handed over to Putin”. 

He believes that Mr Trump will “look at that as a big country and a small country. There’s a big guy in Moscow and there’s this irritating little man in Kyiv. It doesn’t bode well.”

Why Ukraine could fall and how it would happen

• To fight Russia, Ukraine “remains absolutely dependent” on donations of weapons and ammunition from Western allies, according to the Washington-based Institute for the Study of War (ISW). 
• “Air defence, artillery, and anti-armour systems are existential requirements for Ukraine. Ukraine cannot build or acquire enough such systems on its own,” its researcher Prof Frederick Kagan wrote in December. 
• Some of the most crucial armaments include portable air-defence systems to target helicopters and longer-range surface-to-air missiles to deter fighter-bombers. Javelin anti-tank missiles, and artillery systems capable of quickly identifying any incoming shells and firing back, have also been crucial. 
• Stopping the supply of these technologies and other armaments to Ukraine would be disastrous, Prof Kagan predicts. “The most probable scenario is thus that the Russians would begin once again driving Ukrainian forces back, taking larger areas of Ukraine, devastating Ukraine’s cities from the air, and possibly collapsing Ukraine’s ability to fight entirely. There is every reason to believe, in short, that cutting off Western aid to Ukraine would allow Russia to win militarily.”
• There is currently no question of Western military aid being cut off entirely, with Ukraine’s European allies remaining steadfast in their support. Russia also has its own “extreme challenges“, one Western official told the BBC this week. “Russia’s domestic ammunition production capabilities are currently insufficient for meeting the needs of the Ukraine conflict.” 
• But Ukraine is already rationing ammunition and would face much more intense problems if the US backs away. 
• Should Ukraine lose the war, this would increase “the risk of a larger and costlier war in Europe”, according to Prof Kagan’s ISW colleague Nataliya Bugayova. 
• She wrote in December: “A Russian victory would create an ugly world in which the atrocities associated with Russia’s way of war and way of ruling the populations under its control are normalised. Most dangerous of all, however, US adversaries would learn that they can break America’s will to act in support of their strategic interests.” 

@robhastings