The Marines, in Spanish, "Infanteria de Marina", are the marine infantry of the Spanish Navy, the oldest in the world. It has a strength of 5,000 troops divided into base defense forces and landing forces. One of the three base defense battalions is stationed with each of the Navy headquarters. "Groups" (midway between battalions and regiments) are stationed in Madrid and Las Palmas de Gran Canaria. The Tercio (fleet — regiment equivalent) is available for immediate embarkation and based out of San Fernando. Its principal weapons include light tanks, armored combat vehicles, self-propelled artillery, and SPIKE antitank missiles.