Philippine Marines clear a room during Balikatan 2011 as their instructor Cpl. Nicholas Macklin, a military policeman with Military Police Company, Headquarters Battalion, 3rd Marine Division, III Marine Expeditionary Force, supervises on during Balikatan 2011 at Fort Magsaysay, April 8. The Philippine Marines were previously taught military operations on urban terrain but the evolution of the doctrine has triggered a need to evolve.