The Defence Secretary says 97% of Russia's army is involved in the Ukraine war.
Ben Wallace said Russian troops in Ukraine are suffering "almost First World War levels of attrition and with success rates of a matter of metres".
Speaking to BBC Radio 4's Today programme, Mr Wallace said since General Valery Gerasimov was appointed Russia's Chief of the General Staff, "we've seen a sort of effort to advance on all fronts".
"We haven't actually seen this massing of a single force to punch through, a big offensive – just an effort to advance, and that has come at a huge cost to the Russian army," he said.
It comes as defence secretaries from across Nato are meeting in Brussels, with how to accelerate support to Ukraine at the top of the agenda.
Mr Wallace said "helping Ukraine defeat Russia actually adds to our own security at home".
When asked if the UK's support for Ukraine is "weakening" its own army, he told Radio 4: "Not at all, and in fact, I would say it is actually the opposite."
He added that helping Ukraine and weakening the British Army are "not mutually exclusive".
"Helping Ukraine defeat Russia in Ukraine actually adds to our own security at home and as the Ukrainians themselves say: 'We are fighting not just for our freedom, but for your freedom in Europe'.
"If 97% of the Russian army is now committed to Ukraine with an attrition rate very, very high, and potentially their combat effectiveness depleted by 40% and nearly two-thirds of their tanks destroyed or broken, that has a direct impact on the security of Europe."
He added: "It actually says, that those Russian land forces that used to mass in places like Kaliningrad on the border between Poland and the Baltic states or those threats are absolutely in a less threatening position simply because there aren't much left of it."