Crimea was not a non-nuclear zone in an international law sense but was part of Ukraine, a state which doesn't possess nuclear arms.

If you say that your national law allows you to do something, it is fine as long as you do this inside your own territory. As long as you go international, you really have to be sure that there is an international law which you respect and which you follow.

Attempts to settle crises by unilateral sanctions outside the framework of U.N. Security Council decisions threaten international peace and stability. Such attempts are counterproductive and contradict the norms and principles of international law.

I don't believe in ideology in international relations.

Russia has every reason to dispose of its nuclear arsenal... to suit its interests and international legal obligations.

Governments are mandated by international law to protect people from genocide.