Ukraine will send a delegation to Istanbul for a new round of direct peace talks with Russia on Monday, President Volodymyr Zelensky announced Sunday, as the conflict rages on with deadly missile strikes and the largest drone assault of the three-year war.

Ukraine’s recent submission of a ceasefire proposal was met by Russia’s largest aerial assault since the war began, with over 900 drones and 92 missiles targeting Ukrainian cities over three days, killing at least 16 civilians.

Russian and Ukrainian forces exchanged deadly cross-border drone and missile attacks during the overnight hours Sunday into Monday morning despite international diplomatic efforts to end hostilities.