Radak: This is like "va'Yhi Devar Shmuel l'Chol Yisrael" (Shmuel I, 4:1), and when they asked from the Urim v'Tumim, like in the war against Binyamin (Shoftim 20:18, 23), and similarly when there will not be a punishment on them.

Malbim: When they merit, they will go to fight the enemy outside Yerushalayim, in Eretz Yisrael.

Rashi: They face Yerushalayim.