Yet, the danger of nuclear war remains "relatively small" between India and Pakistan, according to Mr Clary. "So long as there is not major ground combat along the border, the dangers of nuclear use remain relatively small and manageable," he said.

India and Pakistan have fought three major wars and been at loggerheads since their independence. The spark for the latest chaos was an April 22 attack in Indian Kashmir that killed 26 people, most of them tourists. New Delhi blamed the incident on "terrorists" backed by Pakistan, a charge denied by Islamabad.

India and Pakistan have been pushed a step closer to war after a gun massacre of tourists on April 22, their most serious confrontation in decades.