Russian air defense systems thwarted four nighttime Ukrainian drone attacks, Russia’s Ministry of Defense said Tuesday, with the falling wreckage of one drone shattering an apartment building’s windows and damaging vehicles in Moscow’s western suburbs.

There were no reports of injuries in the latest drone attacks that Russia blamed on Kyiv, as the war approaches its 18-month milestone.

Though the drone attacks on Russian soil have occurred almost daily in recent weeks, they have caused little damage. Even so, they have unnerved some Russians and are in line with Ukraine President Volodymyr Zelenskyy’s pledge to take the war into the heart of Russia.

Flights at several Moscow airports were temporarily suspended Tuesday as a security precaution amid the attacks, authorities said.

Two other drones were jammed and crashed in the western Bryansk region bordering Ukraine, the defense ministry said.

Ukraine hasn’t acknowledged responsibility for the attempted drone strikes, nor have senior Russian leaders made any comment about the development.

Russian President Vladimir Putin was to speak via video link at a meeting this week in Johannesburg of leaders from Brazil, Russia, India, China and South Africa.

Putin is under threat of arrest if he travels abroad due to an International Criminal Court arrest warrant and won't attend the so-called BRICS talks in person.