US Secretary of State John Kerry has extended the "deepest condolences" to Russia over the crash of a Russian passenger plane in Egypt, which killed 224 people onboard.Kerry spoke to Rusian Foreign Minister Sergey Lavrov on Saturday "to express deepest condolences to the families and friends of those killed in the crash in Egypt of Kogalymavia Flight 9268," US State Department said in a statement.Kerry also offered to provide US assistance, if needed, it added.The Airbus A-321 operated by Russian airline Kogalymavia, with 217 Russian passengers and seven crew members onboard, crashed early Saturday in the Sinai Peninsula shortly after it took off from Egypt's Red Sea Resort Sharm el-Sheikh. No survivor has been reported from the crash.The Sinai-based group "Sinai State" that announced loyalty to the terror group Islamic State (IS) said in a statement posted on Twitter that its militants managed to target the Russian plane and killed all its passengers, in revenge for Russia's recent military operations against the IS in Syria.