While Spain was facing retaliation from the Katipunan during the last few years of the 19th century (the Philippine Revolution lasted from 1896-1898), the empire also faced political unrest in Cuba, another of its territories at the time. Many Americans sympathized with the Cuban revolutionaries for resisting Spanish colonization and the public began to call for U.S. intervention in the conflict. With the explosion of the USS Maine, their wishes were fulfilled as the U.S. blamed Spain for the incident (without a basis for its claims) and declared war on April 21, 1898.

Because Spain was incredibly underprepared for combat with the U.S., within the year Spain and the U.S. drafted the Treaty of Paris. The treaty ceded Spain’s territories to the U.S., including the Philippines.

https://www.history.com/topics/early-20th-century-us/spanish-american-war