Ukraine's allies have been warned over the importance of maintaining supplies to the country as a former supreme Nato commander said Vladimir Putin believes he can triumph in a war of attrition.
Speaking at a Chatham House security conference, experts and officials said the conflict remains a threat to the stability of Europe, even after recent gains by Kyiv's armed forces.
Philip Breedlove, a retired American general who served in Nato's top military post between 2013 and 2016 said while Moscow had depleted its precision weapons and failed to establish air supremacy in two failures of the early campaign, its partial mobilisation showed it was ready for a crude battle of mass artillery and infantry endurance.
"Mr Putin does expect that he can win in the old fashioned way," he told The National. "As long as he can keep Nato and America deterred, as he has us deterred now, he'll grind Ukraine down slowly and over time.
"I believe he's indicated that by what he's doing with this call up. He's not really getting anybody that can drive tanks, fly aeroplanes - all he's doing is getting more infantry to put in front of the cannons and drive them forward."
Martin Przydacz, a deputy Polish foreign minister, told the London think tank that seven months on there was still no realistic prospect of a negotiated end to the conflict that has seen Russia claim four provinces of its neighbour for annexation.
"We should keep supporting Ukraine, providing economic and humanitarian assistance. But most importantly - military equipment," he said. "Ukrainians are motivated to continue their counteroffensive and they need our support.
“We should expect that the war will not end anytime soon."
Gen Breedlove said the Russian military high command had appeared dysfunctional in its leadership of the battle and corruption in the country's arms industry had seen advanced air defence systems fail. "They shot out a huge portion of their precise ammunition early in the battle and they had to turn to the less precise stuff. And then they turned to the really crude stuff," he said. "Frankly this is a Russian way of war. If you look at the way they do it, attrition and artillery barrage is their way of doing business."
Despite these setbacks, he believed Russia would test western support for Ukraine. "At the beginning of the war we kept telling Mr Putin what we're not going to do," he said. "While I understand our senior most leader when he says 'we're going to defend every inch of Nato' I know what he's saying.
"But what does Mr Putin hear? Is everybody else fair game? The fact of the matter is I think at the beginning of this war, we had very good intentions. But our signalling may have been mistaken. And I think that that may have played out in exactly how Mr Putin went forward with this war."
Jonathan Hoyle, the European chief executive of Lockheed Martin, said the ability of western arms manufacturers to overcome supply constraints was open to question. "Western kit beats Russian kit when we have enough of it in the hands of the right people at the right time," he said.