India vs China
India, China and Pakistan, all of them have hundreds of nuclear weapons and missiles capable of carrying them. Nuclear weapons are capable of killing millions in a city but is not very effective against an army which is stretched across vast geographic area. In event of any war between them, the losing party will definitely use nuclear weapon against a large city of winning side. Since it will be swiftly followed by vast retaliation of nuclear weapons by the other side. Hence the losing side will probably dump all of its nuclear arsenal in one go, attacking as may cities as possible. Hoping to destroy retaliation capability and morale of other side. But since the winning side expect the retaliation from the losing side, it will also not wait for other side to use nuclear weapon. Hence if there is any war among India Pakistan or India China where more than remote region is under stake, then both side will use all of their nuclear weapons as soon as such war is inevitable. Th...