Ukrainian forces have used UK-supplied Storm Shadow cruise missiles against Russian targets, the Defence Secretary confirmed.
Ben Wallace declined to give further details about the use of the long-range cruise missile which the UK confirmed it would supply to Ukraine earlier this month.
Ukrainian president Volodymyr Zelensky has lobbied Western leaders to supply Nato fighter jets to his nation, particularly F-16s, which the UK does not possess.
The long-range Storm Shadow missiles have a range of 350 miles and a top speed of 621mph and Mr Wallace suggested they could help provide some of the same capabilities to strike at Russian positions behind the frontline.
At a press conference at the UK's Permanent Joint HQ in Northwood, with his Norwegian counterpart Bjorn Arild Gram, Mr Wallace said: "It is my understanding that it (Storm Shadow) has been used since we announced its deployment to Ukraine."
He added: "It's also one of the mitigations that, if you can't supply fighter aircraft, can you help provide one of the things that fighter aircraft deliver, which is deep strike?
"And yes, we can, we can do that with Storm Shadow."
Defence analyst Dr James Bosbotinis earlier told Forces News that Storm Shadow would be "ideal" for targeting Russian facilities where fuel and munition are stored before being sent to frontline units and for targeting Russian air and naval bases in Crimea.
Each Storm Shadow missile costs £2.2m.
The Defence Secretary warned that Vladimir Putin seemed determined to prolong the war in Ukraine "no matter what the cost" to the Russian people.
Mr Wallace said: "He's on the receiving end of over 250,000 dead or injured of his own troops, over 10,000 armoured vehicles destroyed or captured, he's low on his stocks, his international reputation is pretty much trashed on the rocks, and he is still pressing on.
"So, I'm afraid to say at the moment Russia still seems determined, no matter what the cost to their own people.
"And that's why it's important that Ukraine is not only given the tools to defend itself but also to go to the next step of expelling Russia from its borders.
"I'm not going to speculate when they will do that. We are on the right trajectory of their capability, their training their weapons systems," he added.