Moscow vows to retaliate against Kyiv directly for any strikes on Russian soil

Russia on Friday vowed to ramp up attacks on Ukraine capital city Kyiv in response any Ukrainian military strike on targets within Russia's borders.

"The scale of missile strikes by the Russian Armed Forces on objects in Kyiv will be increased in response to any attacks or sabotage on Russian territory," the Russian Ministry of Defense said, according to Russian state-owned outlet RIA News.

Russia invaded Ukraine on Feb. 24. The Ukrainian military has since begun launching raids on Russian soil. In early April, Ukrainian attack helicopters entered Russian airspace and struck an oil depot in Belgorod, according to the Wall Street Journal.

Sirens blared across Ukraine Thursday night as Moscow attacked targets in every oblast, even in the Ukraine's western edges, far from the battle lines. Several explosions rocked Kyiv.

Ukraine government official Lesia Vasylenko speculated the attacks were the result of Russian leader Vladimir Putin being  "livid" about Ukraine earlier this week sinking the Russian warship Moskva in the Black Sea.

Russia says the ship sank in a storm following the explosion of its ammunition supply.