Ukraine leader defiant as drone strikes hit Russia again

Drones have struck inside Russia's border with Ukraine in the second day of attacks exposing the vulnerability of some of Moscow's most important military sites, experts said.

Ukrainian officials did not formally confirm carrying out drone strikes inside Russia, and they have maintained ambiguity over previous high-profile attacks.

But Britain's Defence Ministry said Russia was likely to consider the attacks on Russian bases more than 500km from the border with Ukraine as "some of the most strategically significant failures of force protection since its invasion of Ukraine".

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Kremlin spokesman Dmitry Peskov said Russian authorities will "take the necessary measures" to enhance protection of key facilities.

Russian bloggers who generally maintain contacts with officials in their country's military criticised the lack of defensive measures.

A fire broke out at an airport in Russia's southern Kursk region that borders Ukraine after a drone hit the facility, the region's governor said on Tuesday.

In a second incident, an industrial plant 80km from the Ukrainian border was also targeted by drones, which missed a fuel depot at the site, Russian independent media reported.

"They will have less aviation equipment after being damaged due to these mysterious explosions," said Yurii Ihnat, spokesman for the Air Force Command of the Armed Forces of Ukraine.

"This is undoubtedly excellent news because if one or two aircraft fail, then in the future, some more aircraft may fail in some way.

"This reduces their capabilities."

Moscow blamed Kyiv for unprecedented attacks on two air bases deep inside Russia a day earlier.

The attacks on the Engels base in the Saratov region on the Volga River and the Dyagilevo base in the Ryazan region in western Russia were some of the most audacious inside Russia during the war.

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In the aftermath, Russian troops carried out another wave of missile strikes on Ukrainian territory that struck homes and buildings and killed civilians, compounding damage done to power and other infrastructure over weeks of missile attacks.

Approximately half of households in the Kyiv region remain without electricity, the regional governor said on Tuesday, while authorities in southern Odesa — which was hard hit Monday — say they have managed to restore power to hospitals and some vital services.

In a new display of defiance, Ukrainian President Volodymyr Zelenskyy travelled near the front line in the eastern Donetsk region. Marking Ukraine's Armed Forces Day, he vowed to push Russian forces out of all of Ukraine's territory.

"Everyone sees your strength and your skill. ... I'm grateful to your parents. They raised real heroes," Zelenskyy said in a video address to Ukrainian forces from the city of Sloviansk, a key Ukrainian stronghold in the east.

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Russia's Defence Ministry charged that the attack was launched with Soviet-made drones.

After the collapse of the Soviet Union in 1991, which split Russia and Ukraine into separate countries, Ukraine inherited some Soviet-designed Tu-141 Strizh drones, which entered service in the 1970s and have a range of 1000km.

They were designed for reconnaissance duties, but can be fitted with a warhead that effectively turns them into a cruise missile.

Unlike modern drones, the Strizh, or Swift, drones can stay in the air only for a limited amount of time and fly straight to a designated target.

Their outdated technology makes the drones easily detectable by modern air defence systems — and easy to shoot down.