(Reuters) – Ukraine said it had carried out a long-range rocket strike against Russian forces and military equipment in southern Ukraine, territory it says it is planning to retake in a counter-offensive using hundreds of thousands of troops. FIGHTING * The death toll under a collapsed apartment block in the Donetsk region town of Chasiv Yar has climbed to 43, with rescue work still not over four days after the building was hit by Russian rocket fire, emergency services said. * At least 12 people were injured in shelling of the southern city of Mykolaiv overnight, the regional governor said. I…