Key Ukrainian infrastructure hit by Russian strikes: officials

Ukrainian officials said on Monday that Russian strikes hit Ukraine's critical infrastructure in Kyiv, Kharkiv and other cities. The strikes appeared to be retaliation for what Moscow alleged was Ukraine's attack over the weekend on Russia's Black Sea Fleet. Loud explosions were heard across the Ukrainian capital of Kyiv early Monday morning. Some residents received text messages from the emergency services about the threat of a missile attack. Air raid sirens were heard for three straight hours.