Political and religious animosity against Jehovah's Witnesses has at times led to mob action and government oppression in various countries. Their doctrine of political neutrality and their refusal to serve in the military has led to imprisonment of members who refused conscription during World War II and at other times where national service has been compulsory. In 1933, there were approximately 20,000 Jehovah's Witnesses in Germany, of whom about 10,000 were later imprisoned. Of those, 2000 were sent to Nazi concentration camps, where they were identified by purple triangles; as many as 1200 died, including 250 who were executed. In Canada, Jehovah's Witnesses were interned in camps along with political dissidents and people of Chinese and Japanese descent. In the former Soviet Union, about 9,300 Jehovah's Witnesses were deported to Siberia as part of Operation North in April 1951. Their religious activities are currently banned or restricted in some countries, including China, Vietnam and some Islamic states.