ever built for the Royal Navy, and will maintain Britain's nuclear-powered submarine fleet capabilities for decades to come. Royal Marines The Royal Marines are the Royal Navy's amphibious troops. Consisting of a single manoeuvre brigade (3 Commando) and various independent units, the Royal Marines specialise in amphibious, arctic, and mountain warfare. Contained within 3 Commando Brigade are three attached army units; 383 Commando Petroleum Troop RLC, 29th Commando Regiment Royal Artillery, a field artillery regiment based in Plymouth, and 24 Commando Regiment Royal Engineers. The Commando Logistic Regiment consists of personnel from the Army, Royal Marines, and Royal Navy. British Army The British Army is made up of the Regular Army and the Army Reserve. The army has a single command structure based at Andover and known as "Army Headquarters". Deployable combat formations consist of two divisions (1st and 3rd Mechanised) and eight brigades. Within the United Kingdom, operational and non-deployable units are administered by two divisions, Force Troops Command, and London District. The Army has 50 battalions (36 regular and 14 reserve) of regular and reserve infantry, organised into 17 regiments. The majority of infantry regiments contains multiple regular and reserve battalions. Modern infantry have diverse capabilities and this is reflected in the varied roles assigned to them. There are four operational roles that infantry battalions can fulfil: air assault, armoured infantry, mechanised infantry, and light role infantry. Regiments and battalions e.g.: the Parachute Regiment, exist within every corps of the Army, functioning as administrative or tactical formations. Armoured regiments are equivalent to an infantry battalion. There are 14 armoured regiments within the army, ten regular and four yeomanry (armoured reserve), of which four are designated as "Armoured", three as "Armoured cavalry", and six as "Light Cavalry". Army 2020 Refine has seen developments which will further modify the Royal Armoured Corps. with two existing regiments forming the core of two new STRIKE Brigades. These two regiments, along with the Armoured Cavalry will be equipped with the "Ajax" armoured fighting vehicle, a new £3.5 billion procurement programme. The Ajax will be employed in the task organisation and roles of both Armoured Cavalry and Medium Armour. With a slight exception of the Household Cavalry, which maintains quasi-autonomy within the Household Division, armoured regiments and their yeomanry counterparts collectively form the Royal Armoured Corps. Arms and support units are also formed into similar collectives organised around specific purposes, such as the Corps