Vladimir Putin is engaging in “barbaric and indiscriminate” tactics targeting civilians, Boris Johnson has said.
The prime minister said the Russian president had “fatally underestimated” the willingness of the Ukrainian people to fight – and the resolve of the West.
Speaking during a visit to Poland, he also said the UK had set aside £220m in humanitarian aid.
Meanwhile, Foreign Secretary Liz Truss has said “nothing and no one is off the table” for further sanctions.
The UK is considering calling for Russia to be expelled from the UN Security Council, the BBC understands.
Mr Johnson said he was “increasingly confident” Russia’s invasion would not succeed, adding that Mr Putin “must fail” in his aims in Ukraine.
During a news conference with his Polish counterpart Mateusz Morawiecki in the Polish capital Warsaw, he said Mr Putin was prepared to “bomb tower blocks, to send missiles into tower blocks, to kill children, as we are seeing in increasing numbers”.
COURTESY BBC