By the second week of May, an ambush on an Indian army patrol acting on a tip-off by a local shepherd in the Batalik sector led to the exposure of the infiltration. Initially with little knowledge of the nature or extent of the encroachment, the Indian troops in the area initially claimed that they would evict them within a few days. However, reports of infiltration elsewhere along the LoC soon made it clear that the entire plan of attack was on a much bigger scale. India responded with Operation Vijay, a mobilisation of 200,000 Indian troops. However, because of the nature of the terrain, division and corps operations could not be mounted; the scale of most fighting was at the regimental or battalion level. In effect, two divisions of the Indian Army, numbering 20,000, along with several thousand from the Paramilitary forces of India and the air force were deployed in the conflict zone.