In order to accomplish the full spectrum of Alliance missions, the NATO Command Structure is supported by the NATO Force Structure. The force structure provides three broad categories of forces, In-Place Forces primarily for Collective Defence and Deployable Forces, both held at graduated readiness levels. The third category known as Long Term Build Up Forces which provide forces generally associated with generation of capabilities for large scale Article 5 operations held at very low readiness.
The majority of Deployable Forces are held at high readiness to support both collective defence Alliance wide and crisis response operations wherever they might occur. The multinational deployable forces are commanded by air, land, maritime and special operations forces headquarters provided by a framework nation or number of nations working in concert. Force packages are built around these headquarters dependent upon the task. These deployable headquarters can command and control forces from the size of a brigade numbering thousands of troops up to a corps of tens of thousands, aircraft to deliver hundreds of sorties per day, or maritime task forces of varying size dependent upon the task.
SACEUR has nine Graduated Readiness Forces (Land) Headquarters under Operational Command. These headquarters are providing support to the International Security Assistance Force in Afghanistan and the NATO Response Force on a rotational basis:
· ARRC Headquarters in the United Kingdom as framework nation.
· Rapid Deployable German-Netherlands Corps Headquarters based on the 1st German-Netherlands Corps Headquarters in Münster, Germany.
· Rapid Deployable Italian Corps Headquarters based on the Italian Rapid Reaction Corps Headquarters in Solbiate Olona, near Milan, Italy.
· Rapid Deployable Spanish Corps Headquarters based on the Spanish Corps Headquarters in Valencia, Spain.
· Rapid Deployable Turkish Corps Headquarters based on the 3rd Turkish Corps Headquarters near Istanbul, Turkey.
· EUROCORPS in Strasbourg, France, sponsored by Belgium, France, Germany, Luxembourg and Spain. EUROCORPS has a different international military status than the other five headquarters but has signed a technical arrangement with Allied Command Operations and can also be committed to NATO missions.
· French Rapid Reaction Corps based in Lille, France.
· NATO Deployable Corps Greece based in Thessaloniki, Greece.
· Multinational Corps Northeast based in Szczecin, Poland.
There are five High Readiness Forces (Maritime) Headquarters which can command and control assigned forces up to the level of a NATO naval task force made up of dozens of warships. Each headquarters provides the Maritime Component Command for the NATO Response Force on a rotational basis. SACEUR has available:
· Headquarters Commander Italian Maritime Forces
· Headquarters Commander Spanish Maritime Forces
· Headquarters Commander United Kingdom Maritime Forces
· Headquarters Commander French Maritime Forces
· Headquarters Naval Striking and Support Forces NATO
There are three deployable High Readiness Forces (Air) Headquarters provided by the United Kingdom, France and Germany, which also provide the Air Component Command for the NATO Response Force on a rotational basis.