EMMA BURROWS, SYLVIE CORBET LONDON — Thousands of European troops will take part in a military exercise in Poland this month to prepare for a hypothetical postwar mission in Ukraine to boost the country’s economy and rebuild its armed forces. But some experts say the deployment may never take place.

The force’s first military exercise, led by Britain and France, is aimed both at testing deployment plans and sending a message to Russia and the Trump administration that European countries are stepping up militarily. Yet the overall mission is plagued with challenges, including the ongoing fighting, questions over American support and the outcome of the upcoming French elections.

Britain and France are both part of a wider political group of 37 nations supporting Ukraine known as the Coalition of the Willing .

Ukrainian President Volodymyr Zelenskyy has repeatedly said that in the event of a peace deal, there must be strong security guarantees from Kyiv’s Western allies, including the United States, to deter Russian President Vladimir Putin from attacking the country again. That’s where this force could come in.

“This exercise shows the UK is stepping up, alongside France and our allies, to prepare for the day peace comes to Ukraine,” British Defense Secretary Wes Streeting said.

Alongside France and Britain, eight other European nations will deploy 2,800 soldiers to Poland to rehearse transporting people and equipment into Poland, conduct joint command and control drills and fly jets and an aerial refueling tanker in preparation to help Ukraine reopen its skies.

If deployed once a ceasefire is in place, the force would help regenerate and strengthen Ukraine’s armed forces, provide the reassurance needed to open the country’s skies and help clear mines in the Black Sea, said Lt. Gen. Tom Bateman, commander of Multinational Force-Ukraine, or MNF-U. Here’s a look at the force and the serious challenges it faces.

All of the European countries involved in the force say they will only deploy once hostilities cease. But for that to happen, there needs to be a ceasefire.

Peace negotiations stalled earlier this year after U.S. President Donald Trump launched his war with Iran , while in September he said he had done a deal with Russia to supply diesel fuel to the U.S. ahead of the midterm elections in an attempt to lower fuel prices, providing a political and economic boost to the Kremlin. Trump also called for the removal of Zelenskyy and demanded Kyiv stop striking Russian energy infrastructure. Trump and his officials also offered confusing messages as to why Starshield — which Ukraine uses for drone strikes and air defense — had been throttled. In September, Zelenskyy said the U.S. had failed to provide warning , as it normally did, of incoming Russian ballistic missile attacks.

While both Ukraine and Russia have signaled their willingness to resume U.S.-brokered peace talks, deep disagreements over territory and security guarantees remain.

For Ukraine and European nations, a critical part of any agreement was a U.S. guarantee that it would support Kyiv with intelligence and help monitor a ceasefire, said Ed Arnold, a Senior Associate Fellow at the RUSI military think tank in London.

But now, “the US are basically supporting Russia against Ukraine,” Arnold said, suggesting a lasting ceasefire could be a long way off.

The troops will rehearse transporting people and equipment into Poland, conduct joint command and control drills and fly jets and an aerial refueling tanker in preparation to help Ukraine reopen its skies, the British and French defense ministries said.

The initial idea of the Coalition of the Willing group of nations was to provide Ukraine with security guarantees similar to NATO’s Article 5, in which allies treat an attack against one member as an attack against the entire alliance and discuss how they would respond together, said Federico Santopinto, senior research fellow at the French Institute for International and Strategic Affairs in Paris.

NATO could have offered such security guarantees, but the U.S. and Germany refused that option, which is why France and the U.K. decided to go ahead with plans for a separate European proposal of countries willing to come to Ukraine’s aid if necessary, a French official said, speaking on condition of anonymity to discuss sensitive military details. But the European deployment will not be a NATO force, peacekeeping or ceasefire monitoring mission and is “not designed for offensive operations.”

Rather it is aimed at helping Ukraine deter future Russian aggression, said Bateman, the force commander.

The exercise in Poland was planned earlier this year but is taking place at a time when several European nations, including Poland, have warned of the rising threat from Russian covert activity, including sabotage, espionage and drone incursions.

Denmark’s Defense Intelligence Service said Putin may carry out military attacks against NATO only if he assesses NATO will not respond collectively and “especially if Russia assesses that the United States cannot or will not support the European NATO countries in a potential war against Russia.”Last year, Putin said that any foreign troops inside Ukraine would be considered “legitimate targets.”For that reason, any deployment needs to be a “combat force for their own force protection,” Arnold said, suggesting that if soldiers were pulled at the first sign of trouble, it would make Europe look weak.

Santopinto also expressed skepticism about Europeans’ capacity to provide the “credible deterrence” against Russia that Ukraine would need.

“That could mean having to shoot down Russian fighter jets, with the risk of escalation that everyone wants to avoid,” he said. “Would Europeans be prepared to directly intercept drones and missiles launched by Russia into Ukrainian airspace?”In France, meanwhile, next year’s presidential election is raising doubts about whether the proposed force could materialize. Centrist President Emmanuel Macron cannot seek a third consecutive term, and protests have added to the pressures facing his government.

Far-right leader Marine Le Pen, seen as the favorite, has opposed sending troops to Ukraine. Last month, she said she would end financial assistance to Kyiv after six months in office because France “can no longer afford it.”The party of far-left rival Jean-Luc Mélenchon also opposes a deployment. Other contenders on the left and right have warned against escalation, saying they are concerned about a wider European conflict.

“This is a military operation in search of a mission,” facing many challenges, Arnold said. For that reason, he said, there is almost “zero” chance the force will ever deploy to Ukraine.