Balikatan is the name for the annual military exercises between the Philippines and the United States. It is a Tagalog word meaning "shoulder-to-shoulder". The April 2016 10-day exercises is the 32nd iteration of the Balikatan exercises. The exercises have been the cornerstone of Philippines–United States military relations since the U.S. bases in the Philippines closed.
Australian armed forces have participated in Balikatan exercises annually since 2014. Australia has a visiting forces agreement, a type of a status of forces agreement, with the Philippines called Philippines–Australia Status of Visiting Forces Agreement. The Philippines is open to other countries participating provided that they too have a similar forces agreement.
The U.S. acquired the Philippines after the Spanish–American War of 1898 and the subsequent Philippine–American War. The United States granted the Philippines independence in 1946. In 1951, the governments of the United States and the Philippines signed the Mutual Defense Treaty to "strengthen the fabric of peace" in the Pacific by agreeing to defend each other's territory in the case of external attack. In line with this treaty, the United States maintained until 1992 several military bases in the Philippines, including U.S. Naval Base Subic Bay and the Clark Air Base.
In 1998, following the bases' closure, the Visiting Forces Agreement (Philippines – United States) (VFA) was signed which contained guidelines for the conduct and protection of American troops visiting the Philippines and stipulated the terms and conditions for the American military to enter Philippine territory. The VFA is a reciprocal agreement in that also outlines the requirements for Philippine troops visiting the United States.