During a July meeting with US Defense Secretary Lloyd Austin, Philippine President Rodrigo Duterte suspended his controversial decision to end the Visiting Forces Agreement (VFA), a security pact enabling the US military to operate from the Philippines. “A strong, resilient US-Philippine alliance will remain vital to the security, stability, and prosperity of the Indo-Pacific,” said Austin. “A fully restored VFA will help us achieve that goal together.” Manila’s turnabout comes as it confronts a growing Chinese challenge in the South China Sea, while continuously seeking to reap economic benefits from Beijing. The South China Sea rivalry between China and the Philippines has rejuvenated the US-Philippine military alliance, which could play an important role in a potential Taiwan contingency.
Philippine-China Relations under Duterte
After President Rodrigo Duterte took office in 2016, he reoriented his country’s foreign policy towards engagement with Beijing, while launching attacks on the security alliance with Washington. Repeatedly emphasizing his ethnic Chinese heritage and calling China “the only hope for the Philippines economically,” Duterte notably downplayed the Hague’s 2016 ruling against the People’s Republic of China’s (PRC) claims in the South China Sea. He strived to gain Chinese investment through the framework of the “Belt and Road Initiative” (一带一路, formerly “One Belt, One Road”) for Manila’s ambitious “Build, Build, Build” infrastructure plan.  Joint oil and gas exploration projects in the South China Sea were signed during Chinese President Xi Jinping’s (習近平) 2018 visit to the Philippines, though their progress has been stalled.
Amid a warming of relations with China, Duterte’s moves to downgrade relations with the United States were motivated by Washington’s criticism of his bloody drug war and the Philippine’s deteriorating human rights situation. In 2016, Duterte threatened to end the implementation of the 2014 Enhanced Defense Cooperation Agreement (EDCA), which enables US forces to access Philippine military bases. Later, in February 2020, the Philippine president decided to abrogate the US-Philippine VFA, after Washington had canceled Philippine Senator Ronald dela Rosa’s visa for his role in implementing Duterte’s drug war as a former chief of national police.
Moreover, Manila was dissatisfied with how Washington was handling the South China Sea disputes. From Manila’s perspective, the VFA signed in 1998 was intended to deter Chinese expansionism in the South China Sea. However, China occupied Scarborough Shoal (also known as Huangyan Island, 黃岩島) in 2012 and later built a large military base on Mischief Reef (美濟礁), both of which are claimed by the Philippines. The United States’ Freedom of Navigation Operations did not deter China from occupying the disputed islands and reefs.
Yet, canceling the VFA is counterproductive to asserting Manila’s maritime claims in the South China Sea. The Philippine military, as the weaker player facing the People’s Liberation Army (PLA), needs external military support from the United States. Removing the VFA, and thus potentially creating a gap in the presence of US forces in the Philippines, could embolden China to take more aggressive moves against Manila’s claims in the disputed area. Therefore, on June 1, 2020, in another policy U-turn, Manila informed the US Embassy in Manila that it was freezing its decision to withdraw from the VFA. Philippine Foreign Secretary Teodoro Locsin Jr. said the reversal of the VFA termination was motivated by tensions in the South China Sea, in particular China’s occupation of Scarborough Shoal.
South China Sea Tensions
In March, the Philippines and the United States were alarmed by the massing of more than 200 Chinese ships at Whitsun Reef (牛軛礁, also called the Juan Felipe Reef by Manila) in the Spratly archipelago and the Chinese military’s incursion into the Philippines’ exclusive economic zone (EEZ).  For several weeks, Manila pressed Beijing to withdraw its “maritime militia” vessels from Whitsun Reef. Although these Chinese ships later vacated the reef, the incident has raised Manila’s fears about future Chinese actions in the South China Sea.
Indeed, the ongoing tensions in the South China Sea with China have pushed the Philippines back towards utilizing its security alliance with the United States. Manila is keeping the VFA in place, at least for now. However, it remains to be seen how the trilateral relationship will be affected when Duterte steps down as president in 2022—though he may run as a vice-presidential candidate to extend his time in power, and thus continue to influence the country’s foreign policy.
US-Philippine Alliance and Taiwan Strait Security
The recent turnabout to preserve the VFA is arguably an indirect gain for Taiwan’s security over the long run. The Philippines’ geostrategic location on the “first island chain” alongside Japan and Taiwan indicates that it could play a vital role in the US strategy against China and may affect the United States’ ability to effectively respond to crises and contingencies in the region, ranging from the South China Sea and East China Sea to the Taiwan Strait.  In the event of a Chinese invasion of Taiwan, the United States military would likely operate from its bases in Japan—and potentially in the Philippines—to deploy aircraft and other weaponry to the Taiwan Strait, and may also request logistical support from its two Asian allies that are physically closest to Taiwan.
Although it has not received the same level of attention as the US-Japan Security Alliance, the US-Philippine military alliance could be a secondary, albeit important, player in a Taiwan contingency. While US-Philippine military cooperation is primarily motivated by the imperative to deter China’s aggressive activities in the South China Sea, the concurrent Chinese military pressure campaign against Taiwan has created a convergence of the South China Sea dispute with cross-Strait tensions. That is, Manila has interests in utilizing US support under the framework of the 1951 US-Philippine Mutual Defense Treaty (MDT) to safeguard its territorial and maritime claims in the South China Sea. At the same time, the Philippines has obligations under Article II of the MDT to assist the United States with mutual defense, which could be applied during a Taiwan Strait conflict. If the United States intends to help defend Taiwan from a Chinese invasion, then the VFA is important not only to the US-Philippine alliance but also to Taiwan’s national defense.
Furthermore, analysts have pointed to the concern that once Beijing strengthens its control over the South China Sea, it could weaken US power projection in the Indo-Pacific region and thus impact US policies elsewhere in the region, extending to the Taiwan Strait. The US-Philippine partnership against Chinese expansionism in the South China Sea issue, as well as the US-Japan alliance in the East China Sea, has spillover effects on Taiwan Strait security. Therefore, the interconnectedness of regional security issues requires the United States to take the lead in coordinating a region-wide Taiwan Strait strategy with key allies such as Australia, Japan, South Korea, and the Philippines.
According to analyst Bonny Lin, Japan and Australia are the two countries most likely to provide military assistance to the United States to help defend Taiwan. Lin believes that the willingness of the Philippines, South Korea, and Singapore to help the United States in a Taiwan contingency are more uncertain. She argues that these latter countries may aim for neutrality or provide “limited, less conspicuous forms of assistance, such as intelligence-sharing, support for limited humanitarian military operations […] or logistics support.” However, Manila, which has a large migrant worker population in Taiwan, may be more willing to assist in Taiwan’s defense if a sizeable number of Filipinos are killed in a Chinese military assault on the island, Lin said. Furthermore, if the Taiwan Strait conflict were to widen as the Chinese military either launched attacks on or seized disputed territories, such as those in the South China Sea, there could be a more forceful response by regional actors including the Philippines.
Taiwan and the Philippines are rival claimants in the South China Sea. Mistrust between the Taiwan and Philippine militaries, arising from tensions over territorial claims and fisheries disputes in the South China Sea, may complicate the willingness of the Philippine military to come to Taiwan’s defense. Notably, an incident in May 2013 over the killing of a Taiwanese fisherman by a Philippine coast guard ship led to a military showdown: President Ma Ying-jeou (馬英九) dispatched Taiwanese warships to conduct naval maneuvers in the Balintang Channel to apparently teach the weaker Philippine military a lesson.
Indeed, the Philippines has to contend with two more militarily powerful neighbors—China and Taiwan—and a conflict scenario in the Taiwan Strait could affect Manila’s national security interests. A Chinese victory over Taiwan could lead to a stronger and closer Chinese presence in the Luzon Strait. On the other hand, if Taiwan ultimately repels a Chinese invasion and becomes more militarily powerful, Manila may be concerned that Taipei, which does not recognize the Hague’s 2016 ruling in favor of the Philippines, could become increasingly assertive towards disputed territories also claimed by Manila.
In sum, the Philippines’ need for US support to counter Chinese aggression in the South China Sea may end up bolstering Taiwan’s security. Given the interconnectedness of the South China Sea dispute and Taiwan Strait security, Taipei may find it in its interest to enhance military-to-military trust with Manila by mitigating maritime disputes and boosting bilateral engagement on regional security issues. Taipei should also welcome a more active US-Philippine partnership in the South China Sea even if doing so theoretically goes against its territorial claims.
The main point: Manila’s recent decision to scrap the termination of the Visiting Forces Agreement is a boost for the US-Philippine alliance in the face of rising Chinese assertiveness in the South China Sea. A stronger US-Philippine alliance could provide potential security benefits for Taiwan.
 “Senate Armed Services Committee Hearing; the Nomination of Navy Adm. John C. Aquilino to be Commander of the U.S. Indo-Pacific Command.; Testimony by John Aquilino, For Reappointment to the Grade of Admiral and to be Commander, United States Indo-Pacific Command,” Congressional Documents and Publications, March 23, 2021, retrieved from Nexis Uni.
 “Philippines, US Begin Two-Week Joint Military Drill Amid Tensions in South China Sea,” Asian News International, April 12, 2021, retrieved from Nexis Uni.
 “Duterte’s Foreign Policy Shift to Undermine US’ Geopolitical Influence,” Business Monitor Online, September 30, 2016, retrieved from Nexus Uni.