actually Mearsheimer against NATO expansion into Russia sphere. He believe that is unnecessary provocation against Russia. He doesn't think Russia pose any serious threat to the west, whether it is militarily or economically, certainly not technologically. I think he wouldn't mind if NATO is disbanded if it mean the west can ally with Russia. He mainly concerned about China as a serious competitor to the US. The only thing he is wrong about is probably he underestimate the European countries wariness of Russia, especially in former Soviet states in eastern Europe and baltic states. That's why NATO is staying.