Western media reports say the United Kingdom has supplied Ukraine with multiple Storm Shadow cruise missiles, giving Ukrainian forces a new long-range strike capability in advance of a highly anticipated counteroffensive against Russian forces.

According to CNN, UK Defense Secretary Ben Wallace confirmed the transaction on Thursday, calling the donation Ukraine’s “best chance to defend themselves against Russia’s continued brutality.”

The Storm Shadow is reportedly a long-range cruise missile with stealth capabilities and a firing range of over 250 kilometers, jointly developed by the UK and France, which is typically launched from the air. 

The BBC says the missiles are fired from aircraft, so the longer range means Ukrainian pilots will be able to stay further from the frontlines.

Once launched, the Storm Shadow reportedly drops to low altitude to avoid detection by enemy radar, before latching onto its target with an infra-red seeker.

Critically, the Storm Shadow has the range to strike deep into Russian-held territory in Eastern Ukraine. A Western official reportedly told CNN that the UK has received assurances from the Ukrainian government that these missiles will be used only within Ukrainian sovereign territory and not inside Russia. UK officials have made frequent public statements identifying Crimea as Ukrainian sovereign territory, describing it as “illegally annexed.”

The Times reports that sources in the Ukrainian Defense Ministry confirmed that Kyiv is ready to use the missiles to strike annexed Crimea.

The missile is “a real game changer from a range perspective,” a senior US military official told CNN and gives Kyiv a capability it has been requesting since the outset of the war. 

The deployment of the missiles comes as Ukrainian forces prepare to launch a counteroffensive intended to retake Kremlin-held territory in the eastern and the southern parts of the country.

The BBC says the announcement was made in the House of Commons by Mr. Wallace.  The decision follows repeated pleas from Ukraine for more weapons from the West.

“Russia must recognize that its actions alone have led to such systems being provided to Ukraine,” Wallace told the British Parliament, according to Newsweek.  U.K. Prime Minister Rishi Sunak previously said the United Kingdom would “be the first country to provide Ukraine with longer-range weapons.”

Kremlin spokesperson, Dmitry Peskov, said on Thursday that the donation of Storm Shadow missiles “will demand an appropriate response from our military.”