Editor’s note (March 4th 2025): This story has been updated.

In a sleek business tower in Kyiv, a group of engineers huddle over a new, carbon-black drone called Batyar, “the Rogue”. It looks much like the Iranian-Russian Shahed drones that have been terrorising Ukrainian cities for the past few months. With a range of up to 1,500km at a cost of just $25,000 apiece, its optical terrain-recognition system lets it evade most electronic jamming, so it should more than match its Russian rival. It is the result of many joint collaborations by Ukrainian and American firms. What happens when such co-operation ends?

Thanks to the war, Ukraine is now a world leader in the technology of drones, which are more potent than many weapons provided by the West. Yet overall Ukraine has relied heavily on Western and American military support. Mr Trump’s threat to withhold it had already circulated before his fateful meeting with Volodymyr Zelensky in the Oval Office on February 28th. And on March 3rd Mr Trump ordered an immediate pause; two days later intelligence-sharing was cut off too. “No one wants to believe in the worst-case scenario,” said a military source before the American president’s latest declaration. “But there is worry that some items will be simply impossible to replace.”

The key elements of America’s support are not just the actual weapons but also the ability to maintain and repair them; the air-defence missiles that keep cities functioning; the Starlink system that is the backbone of military communications; but the sharing of intelligence may turn out to be the most critical of all.

Ukrainian soldiers know what happens when the flow of American weapons dries up. In late 2023 Mr Trump ordered Republicans in Congress to withhold approval of the next package of military aid. As a result, Ukraine was short of shells for six months. Nazary Kishak, a Ukrainian officer, says he witnessed the result of the hold-up during Russia’s siege of the Ukrainian city of Bakhmut: a ten-to-one advantage in the supply of artillery shells enabled Russia to destroy the city completely amid a needless loss of life.

To some extent Ukraine’s home-made drones can make up for a loss of artillery firepower. But this requires money: the local defence industry is running below full capacity. Drones have been effective and relatively cheap, but artillery is still needed and shells are too few. The loss of American Bradley fighting vehicles will be damaging, too. The end of American GPS-guided rockets would give Russia freedom of manoeuvre behind the front lines. Lieutenant Kishak says a stop order on such weapons will lead to “more Bakhmuts”.

Only America can produce high-end weapons like the Patriot missiles that have intercepted the Russian hypersonic and ballistic missiles raining down on Ukraine’s cities. On paper the French-Italian SAMP/T system could replace them if it were produced at scale. But it would not knock out Russia’s fastest missiles (though a more advanced version is expected next year). Without the Patriots, more of Ukraine will face the battering of cities near the front, such as Kharkiv. America has been working with Japan to co-produce Patriots, but probably in modest numbers. And Mr Trump would have to approve a transfer, which he might refuse.

The Starlink satellite network, paid for by Poland but controlled by America, is irreplaceable too. The Ukrainians have produced workarounds, for instance during their incursion into Russia’s Kursk region, where most Starlink systems have been disabled. A Ukrainian official says a backup using similar technology is in the works: “We have one to roll out in days; a more extensive solution in three months.” But the switch will be tricky and will remove a key battlefield advantage. Alternatives are inferior in vital respects and vulnerable to Russian electronic warfare.

Most vital of all has been American intelligence, also suspended on March 5th. It has warned Ukrainians when Russian planes are set to strike; forewarned them of new incursions; tracked the flow of Russian, Iranian and North Korean weapons; and enabled them to hit stores, logistics and operational hubs. It has also guided Ukraine’s rockets and drones to targets deep inside Russia. Ukrainian drones can see for a short distance behind the front lines, but American eyes have let them peer much deeper. A Western military official says Europeans might provide some alternatives—Britain, for example, routinely flies surveillance aircraft over the Black Sea—but not as fast. “With this kind of warfare, it’s all about timing. Without US intelligence, Ukraine will struggle with dynamic targeting” to hit new targets as soon as they pop up.

Despite these omens, Ukraine’s top brass have not given way to despair. For one thing, they tell themselves, Mr Trump’s decision could be reversed or watered down. And there is a quiet confidence that the eastern front is fairly stable. “There will be a slow decline, and perhaps the front line may recede somewhat,” says a senior Ukrainian officer. “But there will be no tragedy.” So he hopes. ■

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