Supplies

Before the rocket attack, this building was a large government building.

 The building was actually behind the American lines.

 So the enemy rockets fell on empty buildings.

Now the troops have pulled forward in an effort to conduct a spoiling attack.

The front line troops are re-supplied by man carried supplies.

The lack of vehicles means the troops can be re-supplied more surreptitiously. 

Still, it's a dangerous business to sneak in during broad daylight.