By Tom Balmforth and Pavel Polityuk KYIV (Reuters) -Ukraine said on Tuesday 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. The strike hit an ammunition dump in the town of Nova Kakhovka in the Kherson region and killed 52 people, Ukraine’s military said. It came after Washington supplied Ukraine with advanced HIMARS mobile artillery systems which Kyiv says its forces are using with growing efficiency. The town’s Russia-instal…