Ukraine hit a Moscow oil refinery for a second time in a week and disrupted commercial flights at Moscow airports in one of its biggest drone attacks since Russia’s invasion more than four years ago, Russian officials said Thursday.

The Russian Defense Ministry said that its air defenses overnight shot down 555 Ukrainian drones over multiple regions, with almost 200 intercepted as they were approaching the Russian capital.

Several drones hit the Moscow Oil Refinery on the southeastern outskirts of the city, Moscow Mayor Sergei Sobyanin said.

The Russian Transport Ministry said that flights from four Moscow airports were halted.

The attack came hours after Ukrainian President Volodymyr Zelenskyy said he had held “an important coordination call” with U.S. President Donald Trump and French President Emmanuel Macron that may “bring about significant change.”