The alliance between the United States and the Philippines is "strong and enduring," said US President Joe Biden.

"Today I met with President Marcos of the Philippines. Our nations' relationship is rooted in democracy, common history, and people-to-people ties, including millions of Filipino-Americans who enrich our nation," Biden wrote on a social media post on 22 September, following his bilateral meeting with the Filipino leader.

During their laid-back conversation, Biden acknowledged that despite "some rocky times" in the past, the relationship of the US with the Philippines "remains critical" considering its "very deep roots."

"We have strong ties including millions of Filipino-Americans, who are very proud of their ancestry and desperately want us to continue to have a strong relationship," said Biden.

As they discussed matters of national importance, Biden and Marcos appeared comfortable, with laughter punctuating their talk.

"For decades, our alliance has strengthened both of us, I believe, and one of the things we want to talk about today is how we continue to strengthen them and work together on the things that have a greater concern to you," Biden told Marcos.

The American leader tackled the issue of the South China Sea, stressing his belief that "international waters" must be "respected."

Manila has a long-standing maritime dispute with Beijing in the West Philippine Sea, despite a Permanent Court of Arbitration ruling in favor of the Philippines.

China claims it has jurisdiction to over 80 percent of the South China Sea, including the WPS which is within the Philippines' exclusive economic zone.