Russian President Vladimir Putin is making slow but palpable progress in the Donbas in east Ukraine, British Prime Minister Boris Johnson said .

“I’m afraid that Putin, at great cost to himself and to the Russian military, is continuing to chew through ground in Donbas,” he told Bloomberg UK.

“He’s continuing to make gradual, slow, but I’m afraid palpable, progress and therefore it is absolutely vital that we continue to support the Ukrainians militarily.”

Russia calls its invasion that it launched on Feb. 24 a “special military operation” to demilitarise and “de-nazify” its neighbour. Ukraine and the West say these are false pretexts for a war of aggression.

Johnson said Ukraine needed more military support, including multiple-launch rocket systems, and said the conflict had to end.

“The one way that it can end is for Putin to accept that … the denazification of Ukraine has taken place and he’s able to withdraw with dignity and honour,” he said, adding this did not mean he supported Russia’s premise that there were Nazis in Ukraine.

“I think he has the political margin of manoeuvre to make an end to this,” Johnson said.