Indian and Pakistani soldiers traded fire for 12 hours Tuesday across the heavily armed boundary with Kashmir in what the Indian army called the worst violation of a 2003 cease-fire agreement between the nuclear-armed neighbors. The night-long gunbattle came after one Indian soldier and four Pakistanis were killed Monday along the heavily armed frontier that divides Indian- and Pakistani-controlled Kashmir, the Indian army said. No further casualties were reported Tuesday. India and Pakistan have fought two of their three wars over Kashmir. However, the frontier has been largely quiet since a 2003 cease-fire agreement, which has formed the cornerstone of a peace process between the two countries.