Almost all of Russia’s advance has been halted for several days, despite sustained bombing, the US State Department said. According to this assessment, the Russians have neither air superiority nor control over some of Ukraine’s major cities. This morning, the center of Kyiv was shaken by several powerful explosions, but it is not clear if it was a Russian attack or the noise from the Ukrainian air defense systems, BBC reports. City residents are preparing for a possible siege. Ukraine accuses Russia of bombing civilians. The head of the Organization for Security and Co-operation in Europe (OSCE), Polish Foreign Minister Zbigniew Rau, has described Russia’s attacks on Ukrainian civilians as state terrorism. He believes that Russian troops have begun to attack the civilian population and infrastructure to demoralize the Ukrainians. The diplomat called on Russia to engage in dialogue in order to find a peaceful solution. Negotiations between Ukraine and Russia could resume today.