What a difference a few months can make in geopolitics.

On the surface, Philippine President Ferdinand Marcos Jr. has continued his predecessor’s China policy. Right before declaring his candidacy for the presidency last year, the sole son of the late Filipino strongman openly backed outgoing President Rodrigo Duterte’s strategic subservience to Beijing, since “whatever we do, we can’t go to war.”

Once in power, Marcos has described China as his country’s “strongest partner” for post-pandemic economic recovery and, most recently, praised the Asian powerhouse as a “dependable partner” in infrastructure development. During a meeting with Chinese Foreign Minister Wang Yi, the new Filipino president vowed to continue his predecessor’s China policy in order to usher in a “new golden era” of bilateral relations.

The Philippines’ acting defense chief, Jose Faustino Jr., has underscored his country's commitment to ensuring that bilateral disputes with China in the South China Sea “do not define the entirety of our bilateral relations with China.” The Philippines has also expressed openness to potential resource-sharing agreements in the disputed areas.

Upon closer examination, however, it’s clear that Marcos is overseeing a major shift in Philippine foreign policy toward major powers.

Notwithstanding his cordial rhetoric with Beijing and his convivial exchanges with top Chinese officials, the new Filipino president is rapidly upgrading defense relations with his country’s sole treaty ally, the United States.

In a major geopolitical twist, the Philippines has now emerged as a critical element in Pentagon’s plans to secure Taiwan against a Chinese invasion in the near future.

Throughout the Cold War, the Philippines hosted America’s largest overseas military bases in Subic and Clark. After the collapse of the Soviet Union, however, the two allies fell out over the fate of those bases, which generated significant nationalist and anti-American sentiment in the Philippines.

Following the closure of its bases in the Philippines, the Pentagon continued to maintain a significant presence in the country through rotational access to a variety of bases as well as regular drills with the Philippines military.

Over the past two decades, the focus of the Philippine-U.S. alliance gradually shifted from counterterrorism operations, which were largely concentrated in the southern island of Mindanao, to maritime security cooperation, with growing focus on the South China Sea.

Critical of the Philippines’ dependence on the Pentagon, and eager to forge warm ties with Beijing and Moscow, former President Rodrigo Duterte sought to undermine military cooperation with the United States, culminating in his temporary decision to suspend the Visiting Forces Agreement, a bedrock of bilateral exercises.

Throughout his term in office, the implementation of key bilateral deals — especially the Enhanced Defense Cooperation Agreement — faced bureaucratic and political obstacles. The upshot was a years-long delay in Pentagon’s plans to enhance forward-deployment presence across key Philippine bases as a deterrence against Chinese encroachment in the South China Sea and the broader region.

While Marcos has proven far friendlier to China than his liberal predecessors — especially Benigno Aquino III, who took China to international court over the maritime disputes — he has also welcomed a revitalized alliance with America.

Just months into office, the Filipino president visited the U.S. to ostensibly attend the annual U.N. General Assembly talks. While in New York, however, he not only courted top American companies, but also held a bilateral summit with U.S. President Joe Biden to boost bilateral relations.

During the meeting, the two sides agreed to walk past recent “rocky times,” with the Filipino president going so far as to praise Washington’s stabilizing role in the Indo-Pacific region as “something that is much appreciated by all the countries in the region, and the Philippines especially."

In an earlier meeting with the Filipino-American community in New Jersey, Marcos declared that, “Our relations with the United States remain strong and I believe we will make them stronger in the coming years.”

Meanwhile, the Biden administration has largely soft-pedaled on raising concerns over the good governance and human rights record of the notorious Marcos family. Earlier this year, the State Department assured the new Filipino president that he would enjoy sovereign immunity from pending cases against his family in multiple U.S. courts.

Marcos’ strategic shift goes beyond empty rhetoric. Shortly after Marcos’ visit to the United States, which placed the troubled alliance on an even keel, the Philippine's defense chief traveled to Hawaii to meet U.S. Defense Secretary Lloyd Austin amid a high-stakes defense planning session by the two allies, with major implications for Taiwan.

Under the new Philippine administration, the two allies are expected to dramatically scale up their joint military exercises from around 300 this year to as many as 500 in 2023.

The annual Balikatan (shoulder-to-shoulder) exercises, which often showcase massive war games and amphibious exercises in the South China Sea, will likely see the number of participating troops from the U.S. and the Philippines jumping from around 9,000 in 2022 to as many as 15,000 next year.

By all indications, the Marcos administration has given the green light to the full implementation of the Enhanced Defense Cooperation Agreement, thus granting U.S. troops extensive access to a whole variety of bases across the Philippines. The Biden administration is planning to allocate $70 million for the establishment of critical infrastructure on bases that are expected to host U.S. troops and military hardware under the allies’ defense pact.

The massive upgrade in bilateral military activities are not only meant to enhance interoperability against China’s predatory activities in the South China Sea, but also enhance the Pentagon’s ability to respond to any contingency in nearby Taiwan.

According to Gregory Poling, of the Washington-based Center for Strategic and International Studies, the Philippines now represents "the only piece of territory close enough from which you could hypothetically both monitor and maybe even strike Chinese assets in the southern half of the Strait” since "China has radically changed the status of forces in the South China Sea, which means the U.S. and Japan don't control the southern end of the Taiwan Strait anymore.”

A number of authoritative war games suggest that any Chinese kinetic action would likely concentrate on Taiwan’s southern shores. On one hand, the Pentagon is hoping to shore up Taiwanese defense capabilities through the en masse transfer of modern armaments to the self-ruling nation, which is considered a renegade province by Beijing. But the Philippines, situated to the south of Taiwan, will be pivotal to any successful American deterrence strategy.

After all, the Philippines and Taiwan are separated by only 250 kilometers via the relatively narrow Luzon Strait. The Philippine island of Mavulis, which hosts a Philippine naval detachment, is only 140 kilometers from Taiwan’s southernmost shores. Nearby Fuga Island, part of the Philippine province of Cagayan, also hosts naval forces.

Despite promising “neutrality” in the Taiwan Strait crisis and adopting a “one China” policy, Manila has now expressed its openness to grant the Pentagon access to prized northern bases near the Taiwanese shores. Marcos also echoed a broadly sympathetic position on Taiwan during his meeting with U.S. Secretary of State Blinken earlier this year.

Accordingly, the full implantation of a bilateral defense agreement may soon pave the way for regularized American exercises close to and even institutionalized access to Philippine bases in the north, namely on the islands of Mavulis and Fuga. Last month, the two allies conducted war games in the northernmost islands of the Philippines, underscoring growing focus on the Taiwan crisis.

All of a sudden, the Philippines has gone from one of America’s most prickly allies to one of its most consequential in the Indo-Pacific region.

Richard Javad Heydarian is a senior lecturer at the University of the Philippines, Asian Center and author of, among others, “The Indo-Pacific: Trump, China and the New Struggle for Global Mastery.”