How many countries have nuclear weapons and how many are there? How destructive are today’s nuclear weapons? What about “nuclear deterrence” theory? Do nuclear weapons help keep the peace? What is the New START Agreement and why has Russia suspended its implementation? What is the Treaty on the Prohibition of Nuclear Weapons? Why does this treaty matter if none of the countries with nuclear weapons have joined? Why should one country give up its nuclear weapons if other countries still have them? Why should countries that don’t have nuclear weapons care about this treaty? Can a NATO state join the TPNW? Did Ukraine give up nuclear weapons? What are "tactical" nuclear weapons? What are 'dirty bombs'?

Why does this treaty matter if none of the countries with nuclear weapons have joined?

Answer

The Treaty on the Prohibition of Nuclear Weapons is a powerful normative tool to demonstrate that nuclear weapons are morally unacceptable. It strengthens the legal framework and legal stigma against nuclear weapons. The TPNW can put external pressure on nuclear-armed states to make further efforts on disarmament. 

The TPNW  reinforces other disarmament efforts by nuclear-armed states, such as the ratification of the Comprehensive Test Ban Treaty, further reductions of arsenals, and de-alerting nuclear weapons systems. The TPNW does not preclude or prevent bilateral or multilateral agreements to reduce numbers of warheads between nuclear-armed states.