Drone warfare between Russia and Ukraine intensified over the weekend, with hundreds of drones fired by both sides and air travel in Russia thrown into disarray. The escalation came shortly after Ukrainian President Volodymyr Zelenskyy announced agreements with Western allies and a major US defense firm to boost domestic drone manufacturing, aiming to deliver “hundreds of thousands” of drones this year.

Russia’s Transport Ministry stated that there were major flight disruptions, with hundreds of cancellations and delays at major airports like Moscow’s Sheremetyevo and St. Petersburg’s Pulkovo. Social media photos captured stuck passengers packed into terminals. Russia’s Defense Ministry said that it destroyed 159 Ukrainian drones over Saturday night and Sunday afternoon but did not mention the number launched or damage caused.

Russian missile and drone attacks, meanwhile, continued to pummel Ukraine. Three people were wounded in Kyiv, two in Kharkiv, and four in a glide bomb and drone attack in eastern Kostyantynivka that killed them. Infrastructure at Mykolaiv’s port was targeted, but there were no casualties.

The attacks come after Russia launched a huge attack on Kyiv last week, in which more than 550 drones and missiles were fired during a seven-hour bombing campaign, killing at least two and injuring dozens.

Zelenskyy also announced that he intends to co-produce drones with Denmark, as Ukraine’s European partners work to make up for suspended US arms deliveries. Ukraine has increasingly turned to drones produced domestically to reach deep into Russian territory, such as in a recent attack that was said to have destroyed more than 40 Russian aircraft.

On Friday, Zelenskyy also spoke with US President Donald Trump about joint arms production. Trump subsequently expressed disappointment following an independent conversation with Russian President Vladimir Putin, stating that he could not find any sign that Moscow is serious about ending the war.

The drone surge is a dangerous new stage in the grinding, almost three-year-long conflict.