Expeditionary Joint Strike Force
Each EJSF, colloquially reffed to as a "JSF", is a joint expeditionary quick reaction force, deployed and ready for immediate response to any crisis.
Generally referred to as "First Responders", the core concept of an Expeditionary Strike Force is a basic combat element supplemented with large amounts of support forces. There is a logistics and command element, a Direct Combat Element, and then an Air Support, Naval support, and Ground Support group
Generally, the core group is transported by some form of Amphibious assault ship. This can be anything from a submarine to a super carrier, but generally aircraft carriers and super carriers serve as the main source of transport.
A Joint Strike Force incorporates everything it needs at it's unit level, meaning that the entire unit provides it's own support, logistics, command, and combat forces, and can operate independently from primary control. An EJSF is the smallest self sustaining unit of the Armed Forces, and strangely fits closer into the "Regiment" style of WWII styled military organization of 2000-3000 people. Despite this, the Regiment, as a military unit organization designation, is discontinued in use.
The Expeditionary Joint Strike Forces are generally considered to be composed of "Elite" units, that is units who preform and excel at their particular job. While this is not always necessarily true, most EJSF units are expected to be the largest quick reactionary forces available, allowing a quick operational force to be deployed nearly anywhere in the world, fully capable of combatting their enemies.
While not necessarily Special Forces, EJSF's are expected to be constant active duty units, whom have a large amount of combat and logistics training, and have advanced on to their field of choice. Generally they have spent a large amount of time in the military, having gained rank and seniority among their group, and are equipped with more advanced weapon systems.
While their job is somewhat related to special forces units, these units are essentially highly trained, highly equipped direction action units. They are essentially active duty combat troops, outfitted with the best equipment available, ready and trained for a active duty war.
The JSF are essentially elite conventional warfare units, that is units who preform regularly duties of a conventional combat unit exceptionally well. Sometimes referred to as "Shock Troops", these units essentially are highly trained conventional soldiers, ready to preform active duty combat missions anywhere in the world at a moment's notice.