Earlier this month, Volodymyr Zelensky, the Ukrainian president, made an impassioned plea for fighter jets during a surprise visit to the UK.
Mr Sunak has ordered the Ministry of Defence to look into how planes could be provided and has pledged to train Ukrainian fighter jet pilots.
But military figures have warned that sending the UK’s Typhoon jets would be complicated because training an existing pilot to use one of the jets would normally take three years.
On Monday, Mr Sunak’s two predecessors in Downing Street spoke minutes apart in the Commons and suggested such problems could be overcome.
Mr Johnson said tanks must be sent to Ukraine “in the next few weeks” and not next year, adding: “Let’s cut to the chase and give them the planes too. And if the House was in any doubt about the urgency of supplying our equipment to the Ukrainians, it is becoming ever clearer that China is preparing to arm the Russians.”
On tanks, he said: “The story of the last 12 months is that sooner or later, having exhausted all the other options, we give them what they need – from anti-tank missiles, to Himars, to tanks. And if that is the choice, sooner or later, then for heaven’s sake let’s give these weapons sooner.”
He said it was “absurd” for Western supporters to keep asking the Ukrainians how long the conflict is going to take, adding: “The answer to that question is to a large extent determined by us. It is a fine thing that we’ve finally promised tanks but there is no conceivable ground for delay in getting them to Ukraine.”
Mr Johnson has spearheaded calls to send fighter jets to Ukraine. When Mr Zelensky visited the UK, he urged the Government to send Typhoon jets straight away.
He concluded his speech on Monday by calling on the Government to “designate Russia as a state sponsor of terrorism, placing that country where it now rightly belongs, on the list that includes Cuba, North Korea and Syria”.
He added: “The Ukrainians are not just fighting for their freedom, but for the cause of freedom around the world. We should give them what they need not next month, not next year, but now.”