There is nothing special about the Jewish Defense League. They are pledged to protecting Jews by whatever means they see fit. They have even been labeled as a terrorist organization by the FBI.

formation of new Jewish Communist Defense League in Russian

National-Christian Defense League was created in 1923.

National-Christian Defense League ended in 1935.

The Jewish Defense League is not large enough currently or threatening enough to have this classification, even though the FBI has submitted reports on their domestic US terrorism. However, Kach and Kahane Chai, which is a more populous sister organization of the JDL is recognized as a Terrorist Organization by both the United States and Canada.