Moscow said Tuesday that Ukraine had fired six U.S.-made ATACMS ballistic missiles, six UK-made Storm Shadow cruise missiles and at least 146 drones into Russia in an attack that it said would not go unanswered.

After Ukraine first launched ATACMS and British Storm Shadow missiles into Russia last year, Moscow responded on Nov. 21 by launching a new intermediate-range hypersonic ballistic missile known as “Oreshnik,” or Hazel Tree, at Ukraine.

Russia’s defense ministry said it had shot down all of the Western missiles fired by Ukraine at the Bryansk region, as well as 146 drones outside the war zone. It said two more Storm Shadows had been shot down over the Black Sea.

“The actions of the Kyiv regime, supported by its Western curators, will not go unanswered,” the defense ministry said.

President Vladimir Putin said in November that the Ukraine war was escalating toward a global conflict after the United States and Britain allowed Ukraine for the first time to launch their missiles deep inside Russia.

President-elect Donald Trump has pushed for a ceasefire and negotiations to end the war quickly, leaving Washington’s long-term support for Ukraine in question.

Russia’s 2022 invasion of Ukraine has left tens of thousands of dead, displaced millions and triggered the biggest crisis in relations between Moscow and the West since the 1962 Cuban Missile Crisis.

The drone attack on Russia was one of the biggest to date.

Roman Busargin, governor of the Saratov region about 450 miles southeast of Moscow, said the cities of Saratov and Engels, on opposite banks of the Volga River, had been subjected to a mass drone attack and there was damage to two industrial sites. Schools had shifted to remote learning, he said.

Ukraine attacked the same region last week and claimed to have struck an oil depot serving an airbase for Russian nuclear bomber planes, causing a huge fire that took five days to put out.

The drone attack struck a munitions storage facility holding guided bombs and missiles at the Engels airbase in Russia’s Saratov region as well as other targets, a source in the Security Service of Ukraine said on Tuesday.

The attack caused a large fire at the Aleksinsky chemical plant in the Tula region and a fire at the Saratovsky oil refinery, while the Bryansk chemical plant was also hit, the source said. Reuters could not independently verify the claims of damage.

The source said there had been subsequent detonations at the Bryansk chemical plant as well as a large fire. The operation was conducted by the SBU and Ukraine’s defence forces, the Ukrainian source told Reuters from Kyiv.

Flight restrictions were imposed at airports in Kazan, Saratov, Penza, Ulyanovsk and Nizhnekamsk, Russia’s aviation watchdog said.