naoružavati

1. to arm
   Velike sile naoružavaju obe strane u sukobu. — The great powers are arming both sides in the conflict.
2. (naoružavati se) to arm oneself; to build up arms
   Mnoge zemlje se danas ubrzano naoružavaju. — Many countries are rapidly arming themselves today.
   Pre ispita se naoružavam strpljenjem i kafom. — Before an exam I arm myself with patience and coffee.

The perfective is naoružati; 'to arm oneself with something' takes the instrumental (naoružati se strpljenjem).