The visit is part of recent US efforts to enhance naval ties with Vietnam as it seeks to counter China’s assertiveness over disputed territory in nearby waters. Beijing has reclaimed thousands of acres of land in the South China Sea and increased its military presence in recent years, raising concern from Vietnam and other claimants.

“It sort of speaks to the growing substance of this US-Vietnam defence and security relationship,” said Collin Koh, a research fellow at the S. Rajaratnam School of International Studies in Singapore who studies maritime security. “I think we have seen in more recent years that Vietnam is sliding more toward countries like Japan and the US for obvious reasons that China has risen and grown more assertive.”

The US and Vietnam last week announced the start of its seventh annual naval engagement. The drills beginning in Danang will include maritime exercises focused on communications through the code for unplanned encounters at sea, and a search and rescue operation, according to a statement by the office of the US Commander Logistics Group Western Pacific.

Cam Ranh Bay, located about 354km north of Ho Chi Minh City, has been of strategic significance to the world’s powers for more than 100 years. Built by the French in the 19th century and later occupied by Japan during the second world war, Cam Ranh Bay was offered to the US by its ally South Vietnam in 1965.

The US upgraded the air and naval facilities for use in the war. It was handed back to South Vietnam in 1972 as part of the so-called Vietnamization effort and captured by the communist forces in 1975.

In 2012, Defence Secretary Leon Panetta became the highest-ranking American official to visit Cam Ranh Bay since the Vietnam war.