The U.S. Air Force recently revealed that during 2016 its component of U.S. Cyber Command (USCYBERCOM) conducted 4,000 Cyber War operations to obtain useful information (often about location) on more than 100,000 targets. These included more than 200 HVI (High Value Individuals) that the U.S. wanted to capture or, failing that, kill. Cyber Command relies a lot on ELINT (Electronic Intelligence) and monitoring the Internet to obtain useful information and few details. The air force has some of the best airborne ELINT resources that are also very capable of handling Cyber War missions that also include jamming enemy communications or sending faked information. Details of ELINT and other Internet related operations are rarely released because that would make the techniques less effective. But every part of the military needs some media mention if they want to get the money they need in the budget.
U.S. Cyber Command became operational in late 2010 and headquarters is in Fort Meade (outside Washington, DC). Most of the manpower and capabilities for Cyber Command come from the Cyber War operations the services have already established. U.S. Cyber Command has some smaller organizations of its own that coordinate Cyber War activities among the services, as well as with other branches of the government and commercial organizations that are involved in network security. But most of Cyber Command manpower actually works for the Cyber War organizations of the four services.
Of the four services the U.S. Air Force is the most experienced in Cyber War matters. After 2001 the air force sought to dominate the Cyber War missions. The other services objected and in 2008 the air force officially scrapped its own planned Cyber Command, which was supposed to operate more like USCYBERCOM. That new air force organization led to the original air force Cyber Command plan being scaled back to become the 24th Air Force. This organization handles electronic and Internet based warfare.
The U.S. Army, following the example of the air force, also established a Cyber War operation. Some 21,000 soldiers were pulled from a large variety of signal and intelligence outfits to form ARFORCYBER (Army Forces Cyber Command). It became fully operational in 2012, with its headquarters at Ft. Belvoir, Virginia.
In 2009 the U.S. Navy created an "Information Domination Corps", in the form of a new headquarters (the 10th Fleet), with over 40,000 people reassigned to staff it. While the new Cyber War command mainly deals with intelligence and network security, it will also include meteorology and oceanography. These last two items are very important for deep water navies, especially since a lot of the information about oceans and the weather is kept secret. The fleet called upon the talents of 45,000 sailors and civilians. Most (44,000) of these personnel were reorganized into 10th Fleet jobs or contributed from within other organizations. A thousand new positions were created, mainly for 10th Fleet. All this gave the navy a more powerful and secure position in cyberspace. The navy does not want to repeat the mistakes of the air force in this area.
The U.S. Marine Corps established a Forces Cyberspace Command in 2010, with about 800 personnel, to help provide network security for marine units. The marines are accustomed to doing more with less.
All those Cyber War operations are dependent on contract workers (civilians) for their top technical talent. There is always a shortage of these people, partly because they have to be capable of getting a security clearance. This rules out a lot of the best hacking talent, who had misbehaved in the past and were identified or even prosecuted for it. A lot of otherwise qualified technical personnel won't even apply for these Department of Defense jobs because a background check might reveal earlier hacking misadventures they would rather keep quiet about (at least to the government). Meanwhile, the Department of Defense has assembled a growing group of civilian Cyber War volunteers. Not all have security clearances but in the event of a national Cyber War crisis, that would be less of an issue.