1987 Constitution of the Philippines
Section 25. After the expiration in 1991 of the Agreement between the Republic of the Philippines and the United States of America concerning military bases, foreign military bases, troops, or facilities shall not be allowed in the Philippines except under a treaty duly concurred in by the Senate and, when the Congress so requires, ratified by a majority of the votes cast by the people in a national referendum held for that purpose, and recognized as a treaty by the other contracting State.