MANILA: The historic visit of US Vice President Kamala Harris to a Philippine island off the South China Sea this week was meant to showcase Washington鈥檚 support for one of its oldest security allies in Asia, experts have said, as the Southeast Asian country faced what she called 鈥渋ntimidation and coercion鈥� in the disputed waterway.

Harris鈥� stop on Palawan, an island facing the South China Sea, was part of a three-day visit to the Philippines amid high geopolitical tensions in the region.

She was the highest-ranking American official to have visited the isle, her arrival taking place just days after an incident between the Philippine navy and the Chinese coastguard.

Onboard a Philippine vessel docked in Puerto Princesa bay on Tuesday, Harris said the US and broader international community 鈥渉ave a profound stake in the future of this region.鈥�

鈥淎merica鈥檚 prosperity relies on the billions of dollars that flow through these waters every day. And we are proud to work with you in your mission,鈥� she added.

鈥淎s an ally, the United States stands with the Philippines in the face of intimidation and coercion in the South China Sea.鈥�

The South China Sea is a strategic and resource-rich waterway claimed by China almost in its entirety, but other countries, including the Philippines, Vietnam, Malaysia, and Brunei, also have overlapping claims.

In 2016, an international tribunal in The Hague dismissed China鈥檚 sweeping claim, a ruling that was rejected by Beijing as it continued to send fishing vessels and raise structures in the region, part of which is a Philippine exclusive economic zone.

A Philippine military commander said on Monday that a Chinese coastguard ship 鈥渇orcefully retrieved鈥� a piece of rocket that was being towed by a Philippine vessel, a claim that China has denied.

鈥淏eijing just can鈥檛 seem to stop harassing and coercing its smaller neighbors,鈥� Gregory B. Poling, a South China Sea expert from the Center for Strategic and International Studies, told Arab News.

The Philippine government has filed hundreds of diplomatic protests against Chinese activity in the South China Sea in the past few years. Amid increasing tensions with Beijing, the Philippines established in May three coast guard outposts on three islands in the disputed maritime area to monitor ship movements.

Harris鈥� trip also came amid strained relations between China and the US, particularly over Taiwan, the democratically governed island China regards as its own.

鈥�(But) I don鈥檛 think China was a primary audience; the Philippines was,鈥� Poling said. 鈥淚t sends China the same message: That the United States is committed to standing with its ally.

鈥淭he trip sends a message of reassurance to the Philippines, that the United States remains committed to modernizing the alliance and defending Filipino lives and rights in the South China Sea.鈥�

Arsenio Andolong, a spokesperson from the Philippines鈥� Department of National Defense, said Harris鈥� visit sent a strong message that Washington considered Manila 鈥渁n important ally.鈥�

鈥淭he defense department sees this as a really clear message that they will stand by their obligations under the MDT (mutual defense treaty),鈥� Andolong told Arab News.

The treaty is a 70-year-old pact stipulating that the Philippines and US would support each other if either were attacked by an external party.

Harris鈥� trip was 鈥渧aluable鈥� as it showed how the US 鈥渨ill live up to its obligations鈥� under the treaty, Stephen Cutler, security expert and former FBI legal attache, told Arab News.

鈥淚 also hope that they will go far beyond the military significance,鈥� Cutler said. 鈥淚 think what she does, by coming here and making the kinds of comments that she did, was to show that the United States is interested in a lot more than simply military matters.鈥�