The Naval Infantry Force is the marine corps and amphibious infantry force of the Mexican Navy, founded in 1822. The Marines' main task is to guarantee the maritime security of the country's ports and external and internal defense of the country, and it is trained in sea, air, and land operations. Between 2007 and 2009, the Marines were reorganized into 30 Naval Infantry Battalions, a paratroop battalion, a battalion attached to the Presidential Guard Brigade, two Fast Reaction Forces with six battalions each, and three special forces groups, giving the force a total strength of 25,000 troops.