Pakistan, India, and China have all had nukes for decades, and are all mortal enemies, and there've even been multiple border skirmishes between pairs, without

Pakistan, India, and China have all had nukes for decades, and are all mortal enemies, and there've even been multiple border skirmishes between pairs, without it ever escalating to open war, let alone nukes. No matter how belligerent Iran seems, it's not obvious that their possession of nuclear weapons decreases stability in the region; arguably, with Israel being the other nuclear power in the region, it increases stability by creating a MAD circumstance, where before Israel felt safe taking unilateral military action, protected by its nuclear umbrella.