The Commonwealth, made up of 54 nations of which 32 are small states, should be deeply concerned at the grave threat to the international legal order caused by Russia’s invasion of Ukraine, and should act together to show strong disapproval.This was the theme of a lecture I delivered at the Royal College of Defence Studies in London, on March 7, to over 100 high-level government and military participants from 47 countries, 14 of which were Commonwealth members.  This week’s commentary is a brief outline of some of the points in a 45-minute lecture .Russian military forces have invaded the sovereign territory of Ukraine in violation of the agreed principles of the United Nations and of international law.  In the words of a distinguished group of international lawyers and academics, on March 4: “President Putin’s decision to launch attacks on Ukraine poses a grave challenge to the post-1945 international order. He has sought to replace the rule of law and principles of self-determination for all peoples by the use of force” .In almost every international forum, the actions of the Russian government have been roundly condemned, and many governments have instituted measures not only to register their strong disapproval, but also to penalize the Russian government.