When Russia introduced self-destructing drones from Iran into its war against Ukraine three years ago, Moscow made headlines around the world by launching 43 of them into Ukraine in a single strike.

This month, in just one night, Russia sent more than 800 exploding drones and decoys swarming across the border.

The drastic increase is a result of huge production jumps in Russia for one-way attack drones, which are prioritized by President Vladimir V. Putin and are now being assembled domestically at two main facilities The Kremlin has also pressed through big manufacturing increases in the smaller tactical drones that Russia uses on the front line, enlisting Russian regional governments, factories and even high school students in the push.

Russia’s supply surges, combined with new technology and tactics, have created a colossal challenge for Ukraine, which enjoyed an advantage in drone warfare early in the war that Moscow has eroded.

Russia is using the attack drones, together with missiles and decoys, to saturate air defenses and mount mass onslaughts on Ukraine’s weapons production facilities, energy infrastructure and cities. Kyiv has made big advances of its own in conducting drone strikes deep into Russia, but the Russian barrages are bigger and more sophisticated, and the Ukrainian military is scrambling to adapt its tactics to defend against them.

The threat spilled over onto NATO territory last week. At least 19 Russian drones flew into Poland late Tuesday and early Wednesday, its government said, with only a small handful shot down. Then on Saturday, Romania’s Defense Ministry said two of its fighter jets had intercepted a drone in Romanian airspace amid Russian attacks on neighboring Ukraine. The two episodes demonstrated the difficulty the Western alliance would face in defending against the types of onslaughts Moscow is now able to muster. In the future, individual Russian assaults could involve thousands of drones.