Speaking in the House of Commons after a video call with Western allies on Tuesday, Johnson said it is "vital that we don't allow Putin to gain momentum," the BBC reported.
"That's why we are stepping up our supply of military hardware of the kind that the Ukrainians particularly need now," he said, as quoted by the British public broadcaster on its website.
"That is what we are giving them, in addition to many other forms of support," Johnson added.
Ukrainian President Volodymyr Zelensky announced on Tuesday that Russian forces had launched their anticipated new offensive in the Donbas region.
Source: IAR, PAP, ukrinform.net, bbc.com