He said this during a telephone conversation with President of Ukraine Volodymyr Zelensky.[167] Johnson launched a warning to Russian mothers, saying that their sons were not likely to return home if President Putin chose to invade Ukraine.[168] Deputy Prime Minister Dominic Raab has said that "there is a very significant risk Russia will invade Ukraine" and urged Putin to "step back from the brink".[169] Foreign Secretary Liz Truss wrote on Twitter that the UK "will not tolerate Kremlin plot to install pro-Russian leadership in Ukraine."[170]