
Ukraine war latest: US to know whether Russia 'serious about peace' with Ukraine in coming weeks, Rubio says
Key developments on April 4: * US to know whether Russia 'serious about peace' with Ukraine in coming weeks, Rubio says * US, Russia make 'significant progress' towards Ukraine ceasefire deal, Kremlin negotiator claims * Trump's team advises against calling Putin until Russia agrees to Ukraine ceasefire, NBC reports * More F-16 jets being