evidence: The Indian army controls all of the 76 kilometres (47 mi) and 2553sq km area long Siachen Glacier and all of its tributary glaciers, as well as all the main passes and heights of the Saltoro Ridge[51] immediately west of the glacier, including Sia La, Bilafond La, and Gyong La—thus holding onto the tactical advantage of high ground.[52][53][54][55][56] Indians have been able to hold on to the tactical advantage of the high ground... Most of India's many outposts are west of the Siachen Glacier along the Saltoro Range. In an academic study with detailed maps and satellite images, co-authored by brigadiers from both the Pakistani and Indian military, pages 16 and 27: "Since 1984, the Indian army has been in physical possession of most of the heights on the Saltoro Range west of the Siachen Glacier, while the Pakistan army has held posts at lower elevations of western slopes of the spurs emanating from the Saltoro ridgeline. The Indian army has secured its position on the ridgeline."[This quote needs a citation]