Tensions were rising on the Sino (really Tibetan) frontier in 1962 as the Chinese were looking to follow on their ill gotten gains in Tibet. Not able to get India to give away its territory at the bargaining table, it invaded to take India's territory away. Nine Chinese division attacked on October 20, 1962. After achieving its territorial objectives, China declared a cease-fire on November 21. Even to this day, Beijing claims virtually all of India's northeast state of Arunachal Pradesh. Who's to say that the Chinese won't threaten the Indians again like they threaten everyone else that they have an illigitimate claim against?
1962 War: Border Tensions (1955-1960)
Onwar.com
GlobalSecurity.org
India Times
THE HIMALAYAN WAR: 1962 INDO-SINO CONFLICT