Betar is an international Revisionist Zionist youth movement founded by Ze'ev Jabotinsky. It peaked at 70,000 members worldwide in 1934, including 40,000 in Poland where it conducted military drilling, Hebrew and English instruction, and organized militias to defend against antisemitic attacks by groups like the ONR. The movement organized illegal immigration (Aliyah Bet) smuggling around 40,000 Jews to Mandatory Palestine between 1937-1944. Members played roles in the Warsaw Ghetto Uprising via ŻZW, Irgun paramilitary activities, and early Israeli military efforts. Influenced by fascist aesthetics with uniforms and salutes, it was historically described as a 'Jewish Fascist' organization with alleged ties to fascist Italy. As of the early 21st century, it had approximately 21,000 members. It experienced a post-1970s decline in Israel due to competition from religious Zionist groups like Bnei Akiva and Gush Emunim. Betar remains active in protests against antisemitism, BDS, and Soviet Jewry oppression. Its US branch, founded in 1929 and revived in June 2023, focuses on aggressive street activism, self-defense training (Magen Betar), campus defense, and doxing pro-Palestinian activists under 'Operation Wrath of Zion'. The US branch has embraced Kahanism, anti-Palestinianism, and Islamophobia, leading to ADL blacklisting, and has supported neo-fascist groups like the Proud Boys while conducting Quran burnings.