Manila says 220 fishing vessels believed to be manned by China's maritime militia were observed anchored side by side at the disputed Whitsun Reef earlier this month.
The move appears to be a show of strength meant to signal the new administration's determination to stand firm against China's steady encroachment in the strategic waterway.
A video for "One Sea" was posted by the Chinese Embassy in Manila in an effort to foster solidarity in the fight against COVID-19. But many Filipinos saw it as Beijing pressing territorial claims.
The vessel, China's second aircraft carrier and the first to be domestically produced, is expected to spend up to a year in sea trials before being handed over to the Chinese navy for commissioning.
The USS Carl Vinson, a nuclear-powered supercarrier, is expected to spend four days at the port of Danang at a time of tensions over China's expansion in the South China Sea.
Despite the president's harsh words on China in the past, the leaders appear friendly and say they will cooperate on North Korea and work toward a balanced trade relationship.
The Liaoning, the only operational aircraft carrier in the Chinese fleet, arrived in the southern port amid recent tensions with U.S. forces in the South China Sea.
Satellite photos show what analysts say is an array of anti-aircraft guns, cruise missile defenses, in nearly identical emplacements on islands created around large reefs.
China isn't disputing the claim. Its foreign minister, Wang Yi, says the country has lawfully deployed "limited, necessary defense facilities" on the island in the South China Sea.
Hanoi and Washington hope to strengthen economic and defense ties, especially in the wake of Beijing's construction on a disputed reef in the South China Sea.
The concern follows reports that China has placed mobile artillery on a reef in the disputed Spratly Islands chain, where Beijing is in the midst of unilateral land reclamation and construction.
Satellite imagery of a coral atoll in the South China Sea shows the reef is growing. A U.S. military official likens Beijing's land reclamation to building a "great wall of sand."
The meeting between foreign ministers on both sides is the first such dialogue in four years after relations were frozen by Beijing in 2011 over a disputed island chain in the East China Sea.