Russia tonight claimed it had seized control of a key battleground in eastern Ukraine after fierce fighting.
Authorities said they had taken control of the final Ukrainian holdout of Lysychans - handing Kremlin forces the last redoubt in Luhansk.
With Donetsk, it is one of the two oblasts making up the Donbas region where soldiers are locked in vicious combat.
America’s top military officer, General Mark Milley, said: “Tactically what’s going on right now is a grinding war of attrition in a relatively small portion, on the eastern portion of Ukraine.”
He added: “There’s very intense fighting going on.”
Russian-backed rebels have been battling Ukrainian government forces since 2014 in an uprising supported by Moscow.
Vladimir Putin was forced to focus on securing territory on Ukraine’s eastern border after his forces’ attempts to take the capital, Kyiv, were repelled following the invasion on February 24 this year.
Britain’s former head of the Army, Gen Lord Dannatt, said there had been a “relentless grind in the Donbas to take Donetsk province and the Luhansk province”.
He added: “( Russia ) are relying on their huge superiority in artillery pounding the provinces of Donetsk and Luhansk and once they are reducing almost everything to rubble, they are sending their troops in to take possession of it and we are going to see that slow grind continue.
“They have very nearly achieved taking Luhansk province and then they will turn their sights to trying to get control of Donetsk.”
Analysts at the Washington-based Institute for the Study of War think tank said Ukrainian forces “likely conducted a deliberate withdrawal from Lysychansk”, allowing Russians to seize the city.
Russian Defence Minister Sergei Shoigu told Putin Luhansk had been “liberated”.
Moscow earlier said its forces had captured villages and encircled the city.
Before the Kremlin claimed victory, Luhansk Governor Serhiy Gaidai wrote on the Telegram app: “The Russians are strengthening their positions in the Lysychansk area, the city is on fire.
“They attacked the city with inexplicably brutal tactics.”
The Kremlin blamed Kyiv for a missile attack on the Russian city of Belgorod near the Ukraine border, which killed at least three people.
Ukraine did not claim responsibility for the assault on the Russian side of the frontier..
Elsewhere, six people were killed and 15 wounded in the eastern Ukrainian city of Sloviansk today after it was blasted by Russian multiple rocket launchers, local officials said.
The attack was the worst shelling to hit the city recently and caused nearly 15 fires, Mayor Vadym Lyakh wrote on Telegram.
US Gen Milley, the chairman of the Joint Chiefs of Staff, refused to rule out a Third World War over Russia’s invasion.
Asked about the possibility, the four-star general said: “We don’t want that, obviously.
“The United States certainly doesn’t, NATO certainly doesn’t.
“I’m not going to discount anything, but I don’t think that we’re on that road.”
He added: “We want to contain the war inside Ukraine and we want to make sure that Ukraine has the means to defend itself.”
In Berlin, German Chancellor Olaf Scholz said allies were discussing what security guarantees could be offered to Kyiv after the war.
But he added: “It is clear that it will not be the same as if someone were a member of NATO.”
Meanwhile, Britain will bolster programmes to strip mines and unexploded weapons from Ukraine under measures to rebuild cities, towns and villages ravaged by the Russians, Foreign Secretary Liz Truss will pledge tomorrow.
She will tell a “recovery conference” in Switzerland the UK will “do everything possible to ensure Ukraine wins the war and recovers”, as the Government commits to a Marshall Plan-style programme - echoing the project used to rebuild Europe after the Second World War.
Ms Truss will say: “We need to be in this for the long haul.”