By Sergiy Karazy VINNYTSIA, Ukraine (Reuters) – Russian missiles struck the Ukrainian city of Vinnytsia far behind the frontlines on Thursday in an attack which Ukrainian officials called a war crime and said had killed at least 23 people, including three children. The strike, which Ukraine said had been carried out with Kalibr cruise missiles launched from a Russian submarine in the Black Sea, came a day after a breakthrough in talks between Moscow and Kyiv to unblock Ukrainian grain exports and underscored how far the two sides remain from a peace settlement. “What is this, if not an open ac…