A crucial road tunnel across the Himalayas was opened by Indian Prime Minister Narendra Modi on Monday, advancing all-weather access northward into disputed high-altitude border zones with adversaries China and Pakistan. Part of a larger infrastructure push in border zones, the Z-Morh or Sonmarg tunnel is 6.4 kilometers (four miles) long and runs beneath a dangerous mountain route that is closed off by snow for four to six months of the year. It serves as a starting point for the year-round opening of the Srinagar-Leh Highway, which would enable the quick deployment of military supplies between Ladakh and Indian-administered Kashmir."Connectivity will greatly improve with the opening of the tunnel here," Modi declared, wearing a jacket to protect himself from the bitter cold, during the ribbon-cutting of the $313 million project, which had taken ten years to build. The world's two most populous countries, China and India, are fierce competitors vying for geopolitical dominance in South Asia, and their shared 3,500-kilometer (2,200-mile) border has long been a source of conflict.