Signals intelligence and counter-intelligence is a narrow view of how computers can impact the battlefield. While the NSA and CIA may have some capability beyond listening in on enemy communications, I question whether the responsibility to make attacks on foreign targets which could be considered acts of war should be left separate from the military.
Weaponizing computers can have a much broader use that would be appropriate for a Cyber Force in addition to military intelligence operations. For example, today we might want to knock out a communications array, a factory, or a power plant in enemy territory. Our options at the moment are to send in missiles, bomber jets, or an elite ground unit. But those aren't always good options. The missiles and bombs could cause unwanted collateral damage to civilians. Missiles and bombers are crazy expensive and so is the cost to get them to the target. The risks to using an elite ground unit are enormous not only to the unit itself but to foreign policy if they are killed or captured.
But a Cyber Force could electronically disrupt or disable a facility through any number of means. This would be far cheaper in terms of financial and human costs. Even if there are counter measures in place for the facility to run offline on a private grid, such an attack could sufficiently hinder it until it can be disabled more permanently.
This is no different than sending a bomber jet instead of an infantry platoon. The goal is to make a surgical strike, the generals need to choose the right tool for the job. For an increasingly large class of technologically advanced targets in increasingly urban areas the military will more often want to employ hackers instead of bombers.
The point, then, was that this will be equally true for enemies wishing to attack the United States. A dedicated team of hackers can easily cause as much or more damage than a fleet of bombers. And the United States can either be ready for it or watch as enemies walk over them with impunity like the United States air force flies over enemies today.