Ukraine carried out “massive” drone strikes on several regions of Russia overnight, local officials there said on Tuesday, in what appeared to be one of the largest recent assaults in a Ukrainian campaign to cripple Russia’s war machine on its home turf.

The attacks, mostly in southwestern Russia, were the latest in a series that have demonstrated Ukraine’s ability to strike deep inside the country, even as Kyiv’s forces face setbacks on their own territory.

Blasts were reported in the border region of Bryansk, and drones also targeted regions well beyond it like Saratov and Tula in western Russia, officials in those areas said.

The Ukrainian military did not immediately comment on the strikes. But Ukraine’s Center for Strategic Communications and Information Security, a government agency, said seven regions of Russia had been attacked and that the targets included military production factories, and oil and gas facilities.

The threat forced at least six cities to restrict their airspace on Tuesday morning, according to a statement from Russia’s Federal Aviation Agency. Those included the cities of Saratov and Engels, which both came under overnight attack.

Two industrial plants sustained damage, Roman V. Busargin, the governor of the Saratov region, wrote on Telegram. “Today Saratov and Engels were subjected to a massive UAV attack,” he said, using another name for drones. “Air defenses eliminated a large number of targets.”