Ukrainian forces last week claimed their first successful use of Western-donated Harpoon anti-ship missiles to engage Russian forces, the British Military Intelligence said on Tuesday.
"The target of the attack was almost certainly the Russian naval tug Spasatel Vasily Bekh, which was delivering weapons and personnel to Snake Island in the north-western Black Sea," the defense ministry said in its daily Twitter update.
The war has entered a brutal attritional phase in recent weeks, with Russian forces concentrating on Ukrainian-controlled parts of the Donbas, which Russia claims on behalf of separatists.