"It's final," a top Philippine official confirmed to me just hours after President Rodrigo Duterte submitted a formal notice of termination for the country's Visiting Forces Agreement, or VFA, with the U.S.

This crucial defense agreement has been the linchpin of the bilateral alliance since the end of the Cold War, providing the legal framework for the entry and stationing of American troops on Philippine soil. Without the agreement, the countries' 1951 Mutual Defense Treaty is effectively paralyzed.

Although the decision was shocking, it was also unsurprising, following years of acrimonious exchanges between the firebrand Filipino president and key Western allies, Washington foremost among them.

Above all, it is reckless and exposes the Philippines to growing threats from China to the east and the Islamic State, or the IS, terrorist group in the country's south.

The VFA has been critical in a range of crises. During the Haiyan super typhoon in 2013, the U.S. provided extensive and timely humanitarian assistance and disaster relief operations, deploying as many as 13,400 troops, 66 aircraft, an aircraft carrier and a whole host of military assets.

U.S. sailors load relief supplies in Tacloban in November 2013: during the Haiyan super typhoon, the U.S. provided extensive humanitarian assistance. (Handout photo from the U.S. Navy)

The U.S. also provided crucial assistance during the siege of the southern town of Marawi by IS-affiliated elements through the deployment of Special Forces, high-grade weapons, critical intelligence and surveillance drones.

More recently, the U.S. has stepped up its efforts to enhance the Philippines' maritime security capabilities, through expanding defense aid, deepening coast guard cooperation and unambiguously assuring assistance in the event of a conflict in the South China Sea.

The U.S. Coast Guard National Security Cutter Bertholf, left, and the Philippine Coast Guard ship BRP Batangas arrive in Manila after a joint exercise off the South China Sea in May 2019. © AP

During public hearings, Foreign Secretary Teodoro Locsin Jr. made it clear that the "continuance of the agreement is deemed to be more beneficial" to the Philippines, while Defense Secretary Delfin Lorenzana emphasized how "the U.S. forces are always there in times of calamities."

Since the VFA is the software that serves as the operating system of the Mutual Defense Treaty, its abrogation renders the two countries' alliance, in the words of one top military official, "practically useless." More than half of the 318 joint military activities this year, including 10 major war games and joint exercises, could be canceled.

For years, Duterte, known for his anti-Western sentiments, has consistently railed against the American military presence on Philippine soil, especially his home island of Mindanao. The ideological protege of the country's most prominent Muslim nationalist and communist leaders, the Filipino president has largely viewed American soldiers through the prism of neocolonial occupation.

Duterte had to recalibrate his position once president. His main source of concern was the sentiments of the Philippine military, which has maintained robust ties with the Pentagon over the past century and toppled two presidents in the past three decades. The military has opposed Chinese companies' acquisitions in strategic areas and often leaked information to the media to expose China's aggression.

Two elements, however, have strengthened Duterte's resolve to sever defense ties with the U.S., even to the chagrin of the military establishment.

The first is lingering, and partly legitimate, concerns over the U.S.'s reliability as an ally, especially in response to the threat from China. From the U.S.'s minimal assistance during the Philippine-China naval standoff in the Scarborough Shoal in 2012 to its relatively minuscule defense aid, Duterte is among many who have openly questioned the alliance's utility in recent years.

The more decisive factor, however, is the festering diplomatic crisis over human rights. Things came to a head earlier this year when former Philippine Police Chief and current Senator Ronald "Bato" dela Rosa, a key Duterte ally, had his visa revoked by U.S. authorities, likely for his role in Duterte's controversial drug war, which has claimed the lives of thousands of suspected drug dealers.

Ronald dela Rosa, pictured in December 2016, had his visa revoked by U.S. authorities. © Reuters

Under the global Magnitsky Mechanism, legislation aimed at punishing gross human rights abusers across the world, key Duterte officials, if not the president himself, face the prospect of expanding sanctions, including travel bans and asset freezes, by the U.S. and other Western powers.

In response, Duterte threatened to terminate the VFA if the U.S. did not reverse its policy. Initially, many in Washington and Manila hoped that officials, including the defense and foreign secretaries, as well as prominent legislators, would dissuade the president from unilateral abrogation in favor of a formal review -- but to no avail.

Given the high stakes, the allies should negotiate interim measures that will preserve the most critical joint military activities. In the long run, they could also negotiate a new defense deal, which will be mutually beneficial in light of shared strategic interests, under more auspicious circumstances.

What is clear, however, is that Duterte has recklessly exposed his country to a whole host of security challenges without much-needed American assistance. Both China, which has been encroaching into Philippine waters, and the IS, which has been gaining ground in the southern Philippines, stand to gain from his perfunctory, personal decision.

Richard Heydarian is an Asia-based academic, columnist and author of "The Rise of Duterte: A Populist Revolt Against Elite Democracy" and the "The Indo-Pacific: Trump, China and the New Struggle for Global Mastery."