Is it permissible for combatants to break their fast in Ramadan and make it up later?

If the Mujahideen are traveling a distance that permits shortening prayers, then they are allowed to break their fast and must make up for it later. If they are not traveling, then whoever among them is able to combine fasting with Jihad must fast. And whoever is unable to combine the two is allowed to break his fast and must make up for it later.