5 reasons why Ukraine will keep fighting even if Trump walks

U.S. President Donald Trump shocked European capitals last week with an extraordinary ultimatum to Kyiv: Accept Washington’s surprise draft plan to end the war in Ukraine or risk losing American weapons and intelligence.

That plan has since been amended with Ukrainian and European input to be less overtly pro-Russian, but the threat still hangs over Kyiv.

That raises two questions: whether Europe has the capacity to smoothly step in and replace the weapons provided by the U.S., and whether Ukraine can continue fighting without U.S. arms. Short answers: No and yes.

Long answer: POLITICO took a look at five key issues raised by Trump’s ultimatum and what they mean for Ukraine’s war effort.

1. Can Europe simply replace the United States?

No, not in the near term and not at the level Ukraine needs.

Christian Mölling, senior adviser at the European Policy Centre, said Europe can support Ukraine without the U.S., but only “with more risk.” Anything Washington stops providing would have to be “compensated through losses or by changing how Ukraine fights.” And even then, matching the current level of support is “hardly possible.”

Europe supplies Ukraine with ammunition, tanks, fighter jets and much more — but U.S. weapons are still vital.

The most critical gap is air and missile defense. Much of Ukraine’s ability to stop Russia’s ballistic missiles rests on U.S.-made Patriot systems and their PAC-3 missiles, which only the United States produces.

“I would love to say we could do without the United States … but only for some time,” said Mykola Bielieskov, research fellow at Ukraine’s National Institute for Strategic Studies. “Only the United States can produce PAC-3 MSE interceptor missiles.”

The U.S. State Department this month approved a $105 million sale of Patriot interceptors to Ukraine.

Europe does supply Ukraine with the French-Italian SAMP/T air defense system, which has similar capabilities to the Patriot, and will get the upgraded SAMP/NG system next year, but with the Kremlin unleashing devastating attacks against Ukrainian cities almost every day, Ukraine needs every system it can get.

2. How important is intelligence sharing?

Mölling noted that Ukraine’s early detection of incoming missiles relies on dense U.S. satellite and sensor networks that Europe simply doesn’t have. European assets could help “with gaps,” but “it will never be as good.”

Trump briefly halted intelligence sharing with Ukraine in March in an earlier effort to force Kyiv to the negotiating table.

Ukraine does have access to spy satellites thanks to Finnish space company ICEYE, and Europe does have its own intelligence capabilities — just not of the same caliber as the U.S.

Without U.S. aid, both detecting incoming Russian attacks and preparing counter-attacks, like hitting Russian air defense batteries and refineries, would be more difficult.

“Without U.S. help, our ability to deliver long-range strikes on Russia will be critically reduced. It will be very hard for us. But I can proudly say that we have all come a long way, and we will not lose this ability,” a Ukrainian soldier with the country’s Unmanned Systems Forces, identified only by his callsign Linch, said at a conference in Kyiv on Friday.

If the U.S. stopped sharing intelligence, that “would actually lead to more deaths of Ukrainians,” said Maksym Skrypchenko, president of the Kyiv-based Transatlantic Dialogue Center.

Europe could, over time, build more satellites and reconnaissance aircraft. But it would take years just to fulfill the capability targets of European nations let alone help Ukraine. 

3. Isn’t Europe already outspending the U.S.?

Europe is now clearly outspending the United States on Ukraine, but that doesn’t mean it’s in the driver’s seat. 

Kiel Institute data shows that from 2022 to 2024, Washington and Europe each averaged roughly the same level of monthly military commitments to Kyiv. When Trump took office, that changed dramatically: U.S. monthly military aid dropped close to zero, while European governments ramped up to nearly €4 billion per month in the first half of the year and, even after a dip, were still providing several times more than the U.S. through the summer.

Rather than give weapons, the U.S. instead is selling them — and getting allies to foot the bill under the Prioritized Ukraine Requirements List. 

PURL is a shopping list agreed with NATO that sees European governments wiring money straight to U.S. defense companies for weapons Ukraine can’t get elsewhere. It’s a way of ensuring that crucial American weapons keep flowing to Ukraine — and a political means to keep a transactional Trump from abandoning Kyiv.

“Americans are selling Ukraine what is impossible to substitute,” Skrypchenko said, arguing that U.S. industry needs the European market and will want to keep selling Patriots and other unique systems.

But that doesn’t give Europe real control. Mölling said the deeper problem is that Washington no longer treats defense arrangements as reliable contracts. The United States, he argued, “increasingly behaves like a partner that feels free to rewrite terms whenever its political mood shifts,” leaving Europeans exposed. 

4. Will the U.S. really stop selling weapons to Ukraine?

Skrypchenko argued that the commercial logic pushes against a total halt; PURL has $3.5 billion in pledges, and that’s a lot of money for U.S. defense companies to give up. “I don’t think the U.S. will stop selling us weapons at a European cost,” he said.

However, Mölling warned that political authority beats commercial incentives. 

“The U.S. government can stop exports with a single decision,” he said, referring to phases where the Trump administration has stopped deliveries or intelligence sharing in the past. Washington can also, if it wants, block or freeze reexports or slow deliveries overnight to pressure Kyiv or Europe.

That’s already the mood in Washington.

“President Trump stopped the funding of this war, but the United States is still sending or selling a big amount of weapons to NATO. We cannot do that forever,” White House Press Secretary Karoline Leavitt told Fox News on Monday.

5. Could Ukraine continue to fight without the United States?

Ukraine could keep fighting, but the war would immediately enter a far more vulnerable and unpredictable phase.

Russia has been losing thousands of men a week in its slow-moving offensive, and the Ukrainian military has managed to exact a bloody toll thanks to its drone tech and the increased amount of artillery shells it now has.

Ukraine currently has one of Europe’s largest defense industries, producing its own drones, medium- and long-range missiles, artillery systems and ammunition. Ukrainian President Volodymyr Zelenskyy said last month that the country is now producing about 60 percent of what it needs on the battlefront.

 “In three years, we have transformed a small sector into a dynamic industry that has become the foundation of our defense capability,” Deputy Defense Minister Hanna Gvozdiar said on Monday.

Not all of that missing 40 percent comes from the U.S., but enough does that doing without would affect Ukraine’s ability to wage war.

While it does produce cheap counter-drones, Ukraine still has no domestic ability to intercept ballistic missiles. And to keep the pace, Kyiv needs partners to keep financing its domestic defense sector.

“Support from partners is critical for the industry to maintain momentum and expand capacity,” Gvozdiar said.

Mölling also warned that losing U.S. support would force Kyiv to improvise, which would cost lives. Ukraine could continue operating, he said, but only by accepting “more risk” and adjusting tactics in ways that carry a higher cost.

Ukraine’s resilience, however, is not in doubt. Skrypchenko pointed to how Ukraine has stayed in the fight even during severe shortages of air-defense interceptors, ammunition and other weapons and despite sustained Russian missile, bomb and drone barrages.

The country “has not capitulated or fallen,” he said, a sign that Ukrainian forces would keep resisting even if Trump walks away.

Veronika Melkozerova reported from Kyiv.