@Josh31: Kol Torah used to be a Poalei Agudas Yisrael (PAI) Yeshiva, where Zionism was discouraged, but army service was allowed. Most bachurim did not join. Chevron and Shalavim were similar. Now, Kol Torah is very much against bachurim joining up as the social dynamics in Israel are much more polarized between Chareidi and Mizrachi.
As far as I know, Ger does not assur army service and some Chassidim do join up. Vishnitz and Belz outright assur it and Satmar isn’t even a question.