A long-time Pacific ally key to confronting China is tearing up a major military agreement with the US

• President of the Philippines Rodrigo Duterte has decided to end the Visiting Forces Agreement with the US, a decades-old military pact that oversaw the status of US troops in country for joint military exercises and other activities.
• The local Department of Foreign Affairs sent notice to the US Tuesday announcing that it intends to unilaterally terminate the agreement.
• The US Embassy in the Philippines said that "this is a serious step with significant implications for the US-Philippines alliance."
• The move puts hundreds of joint military exercises, as well as counterterrorism activities, South China Sea deterrence missions, and other forms of US security assistance at risk.
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The Philippines, a Pacific ally that has been on the front lines of US efforts to confront and deter China, especially in the contested South China Sea, notified the US Tuesday that it is officially terminating a bilateral agreement on the status of US troops rotating in and out of the country for military exercises.

Finally following through on a threat he has made many times, President of the Philippines Rodrigo Duterte, a critic of the alliance and a proponent of a foreign policy independent of the US, decided to end the 1998 Visiting Forces Agreement (VFA).

"It's about time we rely on ourselves," the president's spokesman said, according to Reuters. "We will strengthen our own defenses and not rely on any other country."

Teodoro Locson Jr., Duterte's foreign secretary, tweeted Tuesday that the Philippine was unilaterally terminating the agreement. The pact will end 180 days after notification of the US.

The US Embassy in the Philippines confirmed in a statement Tuesday that it received notice of the Philippines intent to end the VFA from the Department of Foreign Affairs, CNN reported.

"This is a serious step with significant implications for the US-Philippines alliance," the statement read. "We will carefully consider how best to move forward to advance our shared interests."

The US and the Philippines continue to be bound by the Mutual Defense Treaty and the Enhanced Defense Cooperation Agreement, but hundreds of US military exercises with the Philippines, such as the large-scale Balikatan exercises, are now potentially in jeopardy.

Terminating the VFA also puts US counterterrorism support, deterrence in the South China Sea, and other forms of security assistance at risk.

The move to end the VFA follows a decision by the US to cancel the visa of Philippines Sen. Ronald del Rosa, a key player in Duterte's bloody war on drugs, the extrajudicial killings of which has resulted in the deaths of thousands of suspects and civilian bystanders.

"I'm warning you," Duterte said in a televised address in late January. "If you won't do the correction on this, I will terminate the … Visiting Forces Agreement. I'll end that son of a b----."

The Philippines has been central to the US's efforts to counter China's growing power. Subic Bay gives the US Navy a port to repair and resupply ships that patrol the contested South China Sea, and Air Force A-10 Thunderbolts and Marine F/A-18 Hornets have used nearby Clark Air Base for training. US special operations troops have also assisted the government's campaign against terror networks in the country's south for roughly two decades.

While the VFA is only one part of a collection of security agreements, Philippine officials have expressed concerns that terminating this one agreement could lead to a domino effect.

"If the VFA is terminated, the EDCA cannot stand alone, because the basis of the EDCA is the VFA, and if the VFA is terminated, the EDCA cannot be effective," Philippines Senate Minority Leader Franklin Drilon explained to reporters before Tuesday's announcement, according to CNN.

"If the VFA and EDCA are no longer effective, then the MDT ... would be inutile and would serve no purpose."

Duterte has previously threatened to end the other bilateral agreements and, on more than one occasion, called for the removal of US troops from the Philippines, often in response to American criticisms of his drug war or concerns over US efforts to push the Philippines to confront China.