Advisor to the Ukrainian President: Cease fire is a prerequisite for negotiations between Russia and Ukraine On August 16, Sergei Lechenko, adviser to the President of Ukraine, said that the prerequisite for ending the Russia-Ukraine conflict was to achieve a ceasefire before advancing negotiations. He emphasized that if negotiations are held before the ceasefire, Ukraine may face the risk of extortion, and the ceasefire is a necessary condition for creating space for diplomatic activities.