Why do the Charedim have a problem with Sherut Leumi?

According to Charedi philosophy, a girl should live under her parents' roof, under their supervision, until she marries. The independence of the Sherut Le'umi system is not part of their system. The fact that Sherut Le'umi is run by the zionist state is also objectionable to some Charedim. My daughters did National service (Sherut Le'umi) and I believe it was a healthy experience for them, but I do believe that it is not so for everyone.