There's at least one other well known agency that focuses on cyber security. The uniformed forces might have hackers, sure. The Coast Guard has heavy machine g

There's at least one other well known agency that focuses on cyber security. The uniformed forces might have hackers, sure. The Coast Guard has heavy machine guns, but the US doesn't rely on them for naval defence - it's also got a whole other force (the Navy) which can do the heavy lifting. If the Army doesn't have hackers to win cyber wars, it has hackers because it's a huge organisation that needs internal cyber security expertise.