JOHANNESBURG: Leaders of the BRICS nations - Brazil, Russia, India, China and South Africa - are due to open a summit in Johannesburg on Tuesday where they will weigh expanding membership as some members push to forge the bloc into a counterweight to the West.Heightened global tensions provoked by the Ukraine war and a growing rivalry between China and the United States have added urgency to a drive to strengthen the bloc, which has at times suffered from internal divisions and a lack of coherent vision."An expanded BRICS...