For those states seeking global power, it is almost impossible to get rid of their weapons of mass destruction. 
There is a little trust between the powerful states, and hence, while they are trying to encourage each other not to have nuclear weapons, each is trying to make itself more equipped with such weapons. 
However, it seems less likely that these states use such weapons against each other, but the mere existence of these weapons guarantees the balance of power between them.
 
 AHMAD REZA TAHERI - Political Science