One of the more difficult matters for someone who wants to understand the U.S. military to understand is ASW, anti-submarine warfare. Many different military resources are used to carry it out, the role of each part of the total effort is often less than clear, and the nature of the threat, past and present, is also not always clear. An executive summary of the proceedings of a recent MIT conference on the topic is one of the best introductions to ASW that I have seen.
ASW involves patrol aircraft which try to get glimpses of potential threats in a larger area, submarines that listen over long periods of time for opposing submarines while trying to be quiet, surface ships that historically focused on finding submarines close at hand, and helicopters whihc have the edge of carrying torpedos that can harm a submarine and can't be outrun by a submarine.
* Modern diesel-electric coastal submarines are quieter and smaller than Cold War nuclear submarines, which makes them harder find. Air Independent Propulsion (AIP) models can stay submerged for very long periods of time.
* The U.S. military has reduced its commitment to ASW as it has focused on other missions in the post-Cold War era to focus upon.
* A small number of undetected submarines, which requires only a small amount of resources to maintain once purchased, can deteur a large opposing force and can require a very large commitment of military resources to defeat.
* Advanced weapons can make it possible for a small diesel-electric submarine to do a great deal of miliarily significant damage.
* Learning to operate as a team is particularly important in ASW, and the U.S. has less of an edge in this area than it does in the technology of particular subsystems.
* Opposing submarines are threats not only to the Navy, but to sea lift and commercial traffic in a large area. This can slow deployment of ground troops and their equipment to a theater of operations, and make the conflict harmful to everyone in the region.