India's Prime Minister says the time has come to convert the world's highest battlefield -- Siachen Glacier in Kashmir -- into a mountain of peace. Manmohan Singh spoke on Sunday to Indian troops stationed atop the glacier, becoming the first Indian prime minister to visit the frigid heights, more than 6,000 meters above sea level. No one lives on the glacier except soldiers, but it has become a symbol in India's territorial dispute with Pakistan. Troops from both countries have been fighting over it since India's occupation in 1984. A 2003 ceasefire ended the battles, but icy temperatures, altitude sickness and accidents continue to claim soldiers' lives. Despite his plea for peace, Mr. Singh ruled out any changes to India's borders, saying the issue is one of security and national prestige.