Vytautas have you seen a geographical map of Pakistan in the center there is the Thar desert that consists of flat land. True in the north there is mountains but any India thrust be in the lowlying centre, as someone has already stated. However, Firstly people should look closer to a map and see that any thrust towards Karachi is very difficult due to Salt marshs along the border plus the indus delta that covers a large area includes farmland and mangroove forests. Secondly the central part is desert but along the Indus river the area is heavily irregated, with a variety of width and depth of canals.
Someone mentioned i think it was Argun(sorry if not) on previous pages that the Pak army will not be willing to concede Lahore, which i also believe would be case, thus the Indian divisions would try to cut the nation into two but due to the mighty Indus and the huge irregation network (one of biggest in world) Pakistan with well trained infantry divisions could in theory stop an Indian dividing thrust, plus with other military assets Pakistan could repel any attempt throught this area. Also Pakistan could easily flood the area as like the Germans did in the Rhur valley.
What do you guys think?
P.s I does not matter if you decide it is a Chinese tank painted in Pakistani colours its all good, Pakistan has saved money but just as important it has gained experiance.