The Philippines sent a notice of termination to end the Visiting Forces Agreement (VFA) with the US, which could bring to an end over a decade of military cooperation.
The US Embassy in Manila received the notice on Tuesday, Foreign Minister Teodoro Locsin tweeted.
The VFA was signed in 1999 and allows US and Filippino troops to carry out joint exercises in the Philippines, as well as guaranteeing passage for US military ships and aircraft.
Locsin was ordered to terminate the agreement by the president of the Philippines, Rodrigo Duterte. The president had previously threatened to revoke the military agreement in a row over the US government cancelling the visa of a top official over human rights violations.
The US has yet to respond to the termination of the pact. Locsin, who supports the pact, last week said that ending the agreement would "negatively impact" defense and security in the Philippines.
"Our contribution to regional defense is anchored on our military alliance with the world's last superpower," he added.
How important is the Visiting Forces Agreement?
Terminating the VFA would affect more than 300 joint exercises and other military activities with the US military this year. Locsin warned that ending the VFA could lead to increasing tension in the disputed South China Sea.
The termination of the 1999 agreement would take effect 180 days after Washington received Manila's notice but both could decide to keep the pact during the waiting period, Philippine officials said.