Commentators differ on whether nuclear disarmament would be desirable, but many argue that disarmament is impractical because it could not be verified. Three reasons are often offered for such pessimism. First, nuclear weapons are small and difficult to detect, and one could not be sure that a few weapons had not been hidden away. Second, nuclear weapons are so destructive that a mere handful would confer enormous military and political advantages over non-nuclear adversaries. Finally, nuclear know-how cannot be eliminated, and any nation that had dismantled its nuclear weapons would be capable of quickly assembling a new arsenal from scratch or using civilian nuclear materials. Because of the difficulty of verifying that other states had eliminated all their weapons and providing adequate warning of their rearming, it is argued, states would not agree to disarm in the first place.