Russia’s use Friday of the intermediate-range missile, which was not carrying a nuclear warhead, “constitutes another dangerous and inexplicable escalation of this war, even as the United States is urgently working with Kyiv, other partners and Moscow to end the war through a negotiated settlement,” US Deputy UN Ambassador Tammy Bruce said.

“We condemn Russia’s continuing and intensifying attacks on Ukraine’s energy facilities and other civilian infrastructure,” Bruce continued.

Moscow on Monday said the missile hit an aviation repair factory in the Lviv region, in western Ukraine, and that it was fired in response to Ukraine’s attempt to strike one of Russian President Vladimir Putin’s residences – a claim which Kyiv denies.

Ukraine confirmed the missile was fired on the Lviv region, close to the border with Poland, but did not say whether the plant was struck.

Acting British ambassador James Kariuki called the attack “reckless,” adding that “it threatens regional and international security and carries significant risk of escalation and miscalculation.”

In addition to deploying the Oreshnik missile on Friday, Russia pummeled the capital Kyiv with air strikes, killing at least four people and leaving half the city’s residential buildings without heating during below freezing winter temperatures.