The Philippines maintained its closest military relations with the United States. Close contacts were based on cooperative ventures, such as joint exercises, and on longstanding military links. Military relations were first established in the colonial era when the United States helped the Philippines to develop its military. The United States and the Philippines maintained their relationship as allies during World War II and the postwar period. Most Philippine military institutions were modeled after United States counterparts, and the United States remained the AFP's principal benefactor in 1990, providing substantial funds and training. Formal relations between the armed forces of the two countries were based on two agreements: the 1947 Military Bases Agreement, which provided for United States facilities in the Philippines, and the 1951 Mutual Defense Treaty, between the Republic of the Philippines and the United States of America.

Under the Mutual Defense Treaty, the Philippines and the United States each agreed that "an armed attack in the Pacific Area on either of the Parties would be dangerous to its own peace and safety." Both nations pledged that in such an event each "would act to meet the common danger in accordance with its constitutional processes." The United States government guaranteed to defend the security of the Philippines against external aggression but not necessarily against internal subversion. The treaty was the basis for an annual joint exercise, known as Balikatan, between the two nations.

Signed in 1947 by the government of the newly independent Philippines, the Military Bases Agreement originally provided the United States with ninety-nine years of access. Almost from the beginning, however, several Military Bases Agreement-related issues were the subject of controversy in the Philippines, arousing sometimes strident opposition to the presence of United States bases. Some Filipinos saw the facilities as an infringement on Philippine sovereignty and a vestige of the country's colonial past. Some also charged that the agreement's rules on criminal jurisdiction shielded United States military personnel from Philippine law and that the economic and military aid provided by the United States as compensation was inadequate. Finally, opponents blamed the United States military for conditions in towns around the facilities, which were notorious for their red-light districts and consequent social problems.

Amendments to the text of the Military Bases Agreement addressed some Philippine concerns but did not quell opposition altogether. A 1959 amendment shortened the duration of the agreement with a proviso that either party could terminate the agreement with one year's notice after 1991. Amendments in 1965 revised legal jurisdiction in criminal and civil matters. After long and difficult negotiations in the late 1970s, the agreement again was amended in 1979 to reaffirm Philippine sovereignty over the bases, ensure the United States unhampered access to the facilities, and provide for a thorough review of the agreement every five years. 1000 The first review, in 1983, resulted in several further concessions to Philippine demands for increased sovereignty. The United States also pledged its best efforts to provide the Philippines with US$900 million in economic and military aid over the next five years (1984-88), up from US$500 million over the previous five years. The seven months of negotiation during the 1988 Military Bases Agreement review were highly contentious. The United States agreed to increase efforts to provide the Philippines with US$481 million in aid annually over the two remaining years of the agreement's fixed term.

In 1990 Philippine and United States representatives began a new round of negotiations on the future of United States bases. The 1987 constitution states that a treaty approved by the Philippine Senate is necessary for foreign bases to remain in the country after 1991. Only a few of the twenty-two original United States military facilities established in 1947 remained in the Philippines in 1990. The two most important were the Subic Bay Naval Base, in Zambales Province (and the adjacent naval air station at Cubi Point), and Clark Air Base, a large facility in Pampanga Province, northwest of Manila. Other ancillary facilities included John Hay Air Station in Benguet Province, San Miguel Naval Communications Station in Zambales Province, and Wallace Air Station in La Union Province.

After preliminary talks in May 1990, negotiations began in earnest in September and were continued into 1991. Citing constitutional requirements and the amended Military Bases Agreement, Philippine negotiators notified United States officials early in the talks that, without a new treaty, United States access to the bases would be terminated in 1991. Philippine officials further stated that their goal was to reach agreement on United States military phaseout, a move that would satisfy Philippine sensitivities over sovereignty. At the same time, Philippine officials were anxious to minimize the adverse impact of a United States withdrawal on the bases' 22,000 workers and on the surrounding communities. Before the talks began, a joint Philippine executive-legislative commission drafted a plan for the conversion of the bases to Philippine military and commercial uses. The chief United States negotiator, meanwhile, announced United States plans to withdraw its air fighter wing at Clark Air Base as part of an overall plan to reduce forces in the region.

As part of bases-related compensation, the United States continued to provide financial, equipment, and logistical support to the Philippine military throughout the 1980s. The effect of United States-supplied equipment, training, and logistical support on the AFP would be difficult to overstate. Most Philippine military equipment was of United States design or manufacture, and, despite growing self-reliance and more Philippine purchases from other countries, United States assistance provided for most AFP capital procurement. Also, the United States funded the military education of more than 20,000 Filipinos between 1950 and 1990. In the late 1980s, approximately seventy officers and senior enlisted personnel studied at United States military schools each year. Some Filipinos attended the United States Military Academy at West Point, and a smaller number graduated from United States naval, air force, and coast guard academies.

Military relations with regional neighbors were conducted primarily within the framework of ASEAN. ASEAN had no defense function, however, and its members were committed to establishing a "zone of peace, freedom, and neutrality" in the region. Outside the ASEAN framework, the Philippines conducted joint military training exercises on a bilateral basis with some regional neighbors. In addition, members of the Philippine armed forces trained in Australia, Malaysia, Thailand, and Singapore, as well as in Britain, Germany, and Belgium.

Data as of June 1991