US Vice President Kamala Harris and her husband Doug Emhoff arrive at Ninoy Aquino International Airport in Manila November 20, 2022.
CNN  — 

A Philippine archipelago known for tropical vacations will become the focus of political attention this week when Vice President Kamala Harris becomes the highest ranking US official to visit its main island.

Palawan is home to dive resorts as well as a Philippine military base that Harris will visit on Tuesday, according to a senior administration official, putting her on the edge of the South China Sea, where China has been building military bases – some on islands claimed by the Philippines – in one of the most outward signs of its ambitions in the Pacific.

Harris met with Philippine President Ferdinand Marcos Jr. Monday, with the partners expected to discuss 21 new projects funded by the United States, including more defense sites around the Philippines in locations yet to be revealed – an indication to Beijing that Washington is forging tighter ties with Manila.

The projects are part of the Enhanced Defense Cooperation Agreement (EDCA) between the two countries, which allows US troops to use agreed locations in the Philippines for security exercises and joint military training, the White House said in a statement.

But US-Philippine defense ties run even deeper.

The country used to be home to two of the US military’s largest overseas installations, Clark Air Base and Subic Bay Naval Base, which were transferred to Philippine control in the 1990s. A mutual defense treaty signed in 1951 remains in force, stipulating that both sides would help defend each other if either were attacked by a third party.

Speaking to reporters Monday, Harris reaffirmed Washington’s “unwavering” commitment to the pact. “We must reiterate always that we stand with you in defense of rules and norms, (in the South China Sea),” Harris said, adding that any attack on Philippine vessels in the South China Sea would invoke mutual US defense commitments.

Sitting beside Harris, Marcos Jr. told reporters: “I have said many times, I do not see a future for the Philippines that does not include the United States, and that has come from the very long relationship with the US.”

Ties between the two countries had frayed under former Philippine President Rodrigo Duterte, who sought closer relations with China during his six years in power.

Gregory Poling, a maritime security expert at Washington’s Center for Strategic and International Studies, said the US and the Philippines are moving on from those “rough years.”

Poling said Harris’ visit sends a strong message of support to the Philippines without necessarily threatening Beijing since Harris will be visiting Palawan, which is close to the South China Sea but not one of the contested islands.

“The benefit that the US in the Philippines will see in sending a message that ‘We stand together in the South China Sea’ far outweighs any modest frustration that it will cause in Beijing,” Poling said.

Reaffirming the US-Philippine alliance

Palawan is renowned as a scuba diving and island-hopping getaway, but it is also home to the Antonio Bautista Air Base in Puerto Princesa, the center of the Philippine military command in charge of defending and patrolling its waters around the Spratly Islands.

The Spratly Islands lie in the southern portion of the 1.3 million-square-mile waterway – almost all of which China claims as its sovereign territory based on its interpretation of historical maps.

According to the Asia Maritime Transparency Initiative, the Philippines occupies nine features in the Spratly chain while China occupies seven. But Beijing, which calls the island chain the Nanshas, has built up and fortified much of its claims in the chain, including building military bases on places like Subi Reef, Johnson Reef, Mischief Reef and Fiery Cross Reef.

In contrast, only one of the Philippine-controlled features even has a runway, Thitu Reef.

Other neighbors surrounding the resource-rich waterway also lay claim to parts of the area, including Vietnam, Taiwan, Brunei and Malaysia.

In 2016, a tribunal in The Hague ruled in favor of the Philippines in a maritime dispute, concluding China has no legal basis to claim historic rights to the bulk of the South China Sea.

Despite the ruling, Duterte attempted to forge closer ties with Beijing and made plans to cooperate on oil and gas exploration in the South China Sea, a move which divided Filipinos over the legitimacy of enabling China’s ambitions in the disputed territory.

However, the exploration deals were formally terminated in June 2022 due to constitutional challenges and concerns about Philippine sovereignty, former Foreign Minister Teddy Locsin Jr. said before leaving office under Duterte.

Since taking office in June, Marcos Jr. has sought to reset ties with the US and restart amicable communications with China, both on economic and security issues.

On the sidelines of the APEC meeting last Thursday, Marcos Jr. and Chinese leader Xi Jinping both agreed that maritime issues “do not define the totality of Philippines-China relations,” according to the Philippine press secretary.

“Our foreign policy refuses to fall into the trap of a Cold War mindset. Ours is an independent foreign policy guided by our national interest and commitment to peace,” said Marcos Jr.

A tight balance over the South China Sea

As a defense ally to Washington and a competing claimant over Beijing’s sweeping territorial claims over the South China Sea, the Philippines is critical to both Washington’s strategy in the region and China’s geopolitical rise.

Rommel Banlaoi, president of the Philippine Association for Chinese Studies, said Marcos Jr.’s big task is to strengthen and modernize the country’s defense system – with the help of the US – while establishing amicable dialogue with China to bolster economic ties with its largest trade partner.

“Philippine President Marcos appears open to the idea of pursuing pragmatic cooperation in the South China Sea, while not surrendering its long-standing position when it comes to the territorial issues in the South China Sea,” Banlaoi said.

During her trip to the Philippines, Harris is expected to make a number of other announcements including tighter US cooperation with Manila on clean energy, cybersecurity, communication and agriculture.

The deals show US intent in the Pacific region, but one South China Sea expert said Harris’ trip to the military base risks aggravating Beijing to the potential detriment of the Philippines.

Anna Malindog-Uy, vice president of the Asian Century Philippines Strategic Studies Institute (ACPSSI), views the visit as “quite a provocative, rabble-rousing, and inflammatory act.”

“It will put my country, the Philippines, in a precarious and awkward situation vis-à-vis Beijing,” she said.

“I don’t see this as beneficial to my country. It is akin to provoking Beijing at the expense of my country, and I don’t think this is something enlightened and nationalist Filipinos will be happy about.”

CNN’s Brad Lendon and Jasmine Wright contributed reporting.