The attacks, which Ukraine didn't acknowledge in keeping with its security policy, reflected a pattern of more frequent and deeper cross-border strikes the Kyiv government has launched since starting a counteroffensive against Russian forces in June.

A precursor and the most dramatic of the strikes happened in May on the Kremlin itself, the seat of power in the capital, Moscow. Sunday's was the fourth such strike on the capital region this month and the third this week, showing Moscow's vulnerability as Russia's war in Ukraine drags into its 18th month.

The Russian Defence Ministry said three drones targeted the city in an “attempted terrorist attack by the Kyiv regime”. Air defences shot down one drone in Odintsovo in the surrounding Moscow region, while two others were jammed and crashed into the Moscow City business district.

Photos and video showed that a drone had ripped off part of the facade of a modern skyscraper, IQ-Quarter, located 7.2 kms (4.5 miles) from the Kremlin. When the drone hit, sparks, flames and smoke spewed from the building, with debris falling on the sidewalk and street. Windows were blown out, and metal window frames were mangled. A security guard was injured, Russia's state news agency Tass reported, citing emergency officials. Russia's Ria-Novosti news agency reported the building's tenants included several government agencies.

Flights were temporarily suspended at Moscow's Vnukovo airport, and the airspace over Moscow and the outlying regions was temporarily closed. President Vladimir Putin, who was in his hometown of St. Petersburg at the time of the attempted attacks for meetings with African leaders and a naval celebration, was briefed, his spokesman said.

Ukrainian officials didn't acknowledge the attacks but President Volodymyr Zelenskyy said in his nightly video address: “Gradually, the war is returning to the territory of Russia — to its symbolic centres and military bases, and this is an inevitable, natural and absolutely fair process.” A Ukrainian air force spokesman also didn't claim responsibility but said the Russian people were seeing the consequences of Russia's war in Ukraine.

“All of the people who think the war doesn't concern them' — it's already touching them,” spokesperson Yurii Ihnat told journalists on Sunday.?“There's already a certain mood in Russia: that something is flying in, and loudly,” he said. “There's no discussion of peace or calm in the Russian interior any more. They got what they wanted.”

Ihnat also referenced an early Sunday drone attack on Crimea, Ukrainian territory which Russia occupied and illegally annexed in 2014. The Russian Defence Ministry announced it had shot down 16 Ukrainian drones and neutralised eight others through electronic jamming. No casualties were reported. Zelenskyy has vowed to take back all land Russian forces have occupied, including Crimea, and his efforts have been strengthened by the receipt and deployment of increasingly advanced Western weapons.

In the earlier attacks on Moscow, Russia's Defense Ministry reported shooting down a Ukrainian drone outside the city on Friday. Four days earlier, two drones struck the Russian capital, one of them falling in the centre of the city near the Defence Ministry's headquarters along the Moscow River about 3 kilometers (2 miles) from the Kremlin. The other drone hit an office building in southern Moscow, gutting several upper floors.

In another attack on July 4, the Russian military said air defences downed four drones on Moscow's outskirts and jammed a fifth that was forced down. Russia has also blamed Ukrainian forces for attacking border areas, and on Sunday, the governor of one such region, Bryansk, said a Ukrainian strike damaged a pig breeding complex and injured three people.

In Ukraine, the air force reported Sunday it had destroyed four Russian drones above the Kherson and Dnipropetrovsk regions. Information on the attacks could not be independently verified. Meanwhile, a Russian missile strike late Saturday killed two people and wounded 20 in the city of Sumy in northeast Ukraine. A four-story vocational college building was hit, the Ukrainian Interior Ministry said. Local authorities said that dormitories and teaching buildings were damaged in the blast and a fire that followed.?