Is it permissible for a man to shave his beard out of necessity for fear of harm?

If he has no escape from going to those lands, or if his going there strengthens the Muslims, then there is no harm in him shaving his beard. However, if his going is for worldly gains, or if the harm he is exposed to can be endured, then it is not permissible for him to shave it. And if it is sufficient to ward off harm from himself by trimming his beard and taking from it, then it is not permissible to shave it.