The U.S. Navy Pacific Fleet, which now controls most of the warships in the U.S. Navy has had a lot of embarrassing personnel and leadership problems in the last decade. These only became visible to the general public when there were major mishaps, like ship collisions or anything that involved loss of life. In 2017 these problems became so bad, and public, that the commander of the Pacific Fleet was fired (relieved) for failure to do his job.
Recently it became public that the Pacific Fleet, which not only most American warships but also most navy personnel and overseas bases, suffered a more serious but generally unpublicized problem. Between 2016 and 2018 Pacific Fleet submarines, and their two support ships (or tenders) did not receive the required computer and computer network security inspections. A recent navy-wide audit of cybersecurity found that COMSUBPAC (Pacific Fleet Submarine Command) was unable to get enough qualified cyber security specialists to carry out the required inspections and deal with any problems discovered. Pacific Fleet policy was to concentrate available network security personnel to service surface ships and land installations, which were connected to the Internet all the time. The submarines had no Internet access most of the time because while at sea the nuclear subs rarely operated on the surface. Submarine crews have limited email access, which means no attachments and low risk of malware getting into the submarine network.
The Pacific Fleet was also dependent on the fact that many systems in submarines were independent of each other and the only ship-wide network was based on Linux, which is less frequently attacked by hackers than computers using Windows, Apple OS or Android. The U.S. military, especially the navy, switched from Windows to Linux about fifteen years ago in part because of reduced security risks. But those risks did not disappear, which was why the navy mandated cybersecurity inspections every three years to assess the security of shipboard systems. In a similar fashion and for similar reasons many large companies, especially in banking and finance, also switched to Linux and were the first to realize hackers had noted the shift. Those hacking groups that specialize in attacking large businesses had found it worth the effort to spend more time and money finding exploitable vulnerabilities in Linux. American military cyber security experts noticed this but the Pacific Fleet and COMSUBPAC did not take note of how critical these new vulnerabilities were. The cybersecurity audits provided an early warning of vulnerability because the first thing a hacker that got into a submarine network would do is carry out an extensive, and time consuming, exploration of the network to find vulnerable areas and develop a plan on how to get into those areas to plant hidden system monitors and system destroying software that can be activated remotely or if certain warlike actions are detected.
Many militaries and governments, like China and North Korea, also switched to Linux to reduce network security vulnerability. Chinese military cybersecurity experts have a list of known vulnerabilities and potential ones that their hackers could use to get into U.S. Navy systems. Cybersecurity on submarines is very important because most American nuclear subs are in the Pacific and are a major threat to the growing Chinese fleet.
It wasn’t just the Pacific Fleet commander who was negligent. Higher ranking admirals than the relieved Pacific Fleet commander are also responsible for this problem developing. Some of them were competent enough to order the navy-wide audit, which found a lot of problems the navy would prefer to keep out of the news, at least until they are fixed. The Pacific submarine force cybersecurity problems are still not completely known, much less being fixed.
The current problems in the Pacific Fleet are a side effect of the post-1991 shift of U.S. Navy forces from the Atlantic to the Pacific. During World War II most of the Navy was operating in the Pacific but after 1945, the Atlantic Fleet grew more powerful. This was in preparation for a potential battle with the growing naval power of the Soviet Union. When the Soviet Union dissolved in 1991, their fleet wasted away within a decade. The American Atlantic Fleet no longer had a major opponent. Meanwhile, China, North Korea, Iraq, Afghanistan, and Iran provided plenty of work for the Pacific Fleet, which normally supplied ships for Middle East and South Asian emergencies.
As the Pacific Fleet grew in size the Atlantic Fleet gradually disappeared until it was renamed, and reorganized, into the U.S. Fleet Forces Command, which is responsible for the training, maintenance, and operation of naval forces (ships, aircraft, and land installations) on both coasts plus providing support and coverage of less vital areas. By 2020 there was only the Pacific Fleet and "the rest of the navy."