KYIV, Ukraine (AP) — Ukrainian saboteurs coordinated by Kyiv’s military intelligence services carried out a pair of recent drone attacks that hit parked bomber aircraft at air bases deep inside Russia, Ukraine media claimed Tuesday.

The attacks on Russian airfields on Saturday and Monday destroyed two Russian bombers and damaged two other aircraft, according to Ukrainska Pravda, as the war approaches its 18-month milestone.

That newspaper and Ukraine’s NV news outlet said groups of saboteurs were behind the audacious strikes, which suggest that Ukraine’s scope of action is broadening. It was not possible to verify the claims on the ground.

Ukrainian media attributed two attacks to the saboteurs: a strike Saturday on the Soltsy air base in the Novgorod region in northwestern Russia, about 700 kilometers (360 miles) north of the Ukrainian border, and Monday’s strike against the Shaikovka air base in the southwestern Kaluga region that is about 300 kilometers (180 miles) northeast of the Ukrainian border.

The Russian Defense Ministry acknowledged that the attack on Soltsy damaged one aircraft. It didn’t comment on the reported attack on Shaikovka, but Russian media did.

Ukraine has since early this year sought to take the war into the heart of Russia. It has increasingly targeted Moscow’s military assets behind the front lines in eastern and southern Ukraine and at the same time has launched drones against Moscow, most recently early Tuesday.

Kyiv is also trying to keep up the pressure on the Kremlin along multiple fronts, pursuing a counteroffensive at various points along the 1,500-kilometer (900-mile) front line, as well as diplomatically by obtaining pledges of more weaponry from its Western allies, including F-16 warplanes.

Ukraine’s Deputy Defense Minister Hanna Malyar said in a statement Tuesday that the Ukrainian military have entered the south-eastern village of Robotyne in the frontline Zaporizhzhia region and were coming under continuous shelling by Russian forces.

Ukrainian military intelligence spokesman Andriy Yusov told the Ukrainian LIGA.net news outlet Monday that at least one Russian warplane was damaged in the attack on Shaikovka. He said it was carried out by people who worked in close coordination with Ukrainian military intelligence but gave no further details.

Satellite images from Planet Labs PBC analyzed by The Associated Press showed what appeared to be 10 Tupolev Tu-22M long-range bombers parked on the apron of the Soltsy air base on Aug. 16. By Monday, two days after the attack, all those bombers had left the air base. A large black spot was visible on one of the aprons where one of the Tupolevs had been parked.

Photos purporting to be from the Soltsy air base and published by Russian and Ukrainian media showed a Russian Tu-22M bomber ablaze there after the attack.

Some previous Ukrainian attacks on Russian air bases involved Soviet-designed drones powered by turbojet engines. They have a range of up to 1,000 kilometers (600 miles). But the strikes in recent days apparently used primitive small drones, which would corroborate the possibility that they were launched by saboteurs.

Also, a Russian pensioner walking in a forest about 600km (370 miles) north of the Ukrainian border on Monday came across the remains of a drone painted in the blue and yellow colors of the Ukrainian flag.

Pictures shared on Russian social media channels show that the drone had “glory to Ukraine” inscribed on a broken wing and “glory to the heroes” written on the other wing, the Russian telegram channel Baza said Tuesday.

A Ukrainian sabotage and reconnaissance group also tried to break through the border in Russia’s western Bryansk region bordering Ukraine on Tuesday, according to the local governor.

Their attempt was repelled by Russian border guard units and the National Guard, Gov. Alexander Bogomaz said. His claim could not be independently verified.

After Russia accused Ukrainian saboteurs of crossing into that area of western Russia and firing on villagers last March, Russian President Vladimir Putin ordered the Federal Security Service to tighten border controls.

Meanwhile, a recent spate of drone attacks apparently targeting Moscow continued early Tuesday but were thwarted by Russian air defense systems, Russia’s Ministry of Defense said.

However, falling wreckage of one drone shattered an apartment building’s windows and damaged vehicles in Moscow’s western suburbs.

There were no reports of injuries in the latest drone attacks that Russia blamed on Kyiv,

Though the drone attacks on Russian soil have occurred almost daily in recent weeks, they have caused little damage and no victims.

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 Bryansk region, 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.