Nuclear weapons is definitely more than interesting physics. Notwithstanding that obvious fact, here we will highlight three different physics aspects related to nuclear weapons. First, the physical conditions for ignition and sustained nuclear reactions for fission and fusion is briefly introduced. Next, we present the phenomena that result from the strong explosion – what we in daily terms label the effects of nuclear weapons. Finally, the physics relevant for any future verifiable nuclear disarmament is discussed and current trends in this area presented.