US President Donald Trump and Ukraine’s President Volodymyr Zelensky agreed on Monday that a trilateral meeting includes their Russian counterpart, Vladimir Putin, might be the next step in a flurry of recent diplomatic efforts to halt Moscow’s war against its neighbour. In his third face-to-face meeting with the Ukrainian president in his second term, Trump also dangled the possibility of US troops supporting Ukraine. He added that he would speak to Putin about the plan, a call that reportedly...