The Indian army responded with Operation Vijay, which launched on 26 May 1999. This saw the Indian military fighting thousands of militants and soldiers in the midst of heavy artillery shelling and while facing extremely cold weather, snow and treacherous terrain at the high altitude. Over 500 Indian soldiers were killed in the three-month-long Kargil War, and it is estimated around 600–4,000 Pakistani militants and soldiers died as well. India pushed back the Pakistani militants and Northern Light Infantry soldiers. Almost 70% of the territory was recaptured by India. Vajpayee sent a "secret letter" to U.S. President Bill Clinton that if Pakistani infiltrators did not withdraw from the Indian territory, "we will get them out, one way or the other" - meaning he did not rule out crossing the Line of Control (LoC), or was the use of nuclear weapons.