British SAS troops have trained Ukrainian forces for the first time since the Russian offensive began, Ukrainian commanders told The Times on Friday.

Instructors from the UK were previously withdrawn from the country in February when NATO member states were expecting a Russian attack.

The British now returned to teach locals how to use NLAWs, UK-supplied shoulder-fired anti-tank missile launchers, the paper wrote, citing Captain Yury Myronenko and two other Ukrainian commanders, identified only by their nicknames.

The units which received the training are stationed around Kiev, The Times noted.

“We have received huge military help from Britain,” Myronenko told the paper. “But the people who knew how to use NLAWs were in other places, so we had to go on YouTube to teach ourselves,” he said, adding that the British officers were in their unit two weeks ago.

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The UK Defense Ministry refused to confirm whether British commandos had visited Ukraine. Armed Forces Minister James Heappey, however, said this week that a group of Ukrainian soldiers would travel to the UK for training.

London has been one of Kiev’s primary arms suppliers, sending weapons ranging from anti-tank and anti-aircraft missile systems to armored vehicles. Prime Minister Boris Johnson made a surprise visit to Kiev last week, where he met with Ukrainian President Volodymyr Zelensky and promised more support.

Russia advanced into the neighboring state in late February, following Ukraine’s failure to implement the terms of the Minsk agreements, first signed in 2014, and Moscow’s eventual recognition of the Donbas republics of Donetsk and Lugansk. The German and French brokered Minsk Protocol was designed to give the breakaway regions special status within the Ukrainian state.

The Kremlin has since demanded that Ukraine officially declare itself a neutral state that will never join the US-led NATO military bloc.