"They are anxious about where China is going, and they have wanted for years now to have a better relationship with the United States", CNN analyst and retired U.S. Navy rear admiral John Kirby explained. These events usually involve subject-matter exchanges in topics such as diving, salvage, undersea medicine and medical evacuations.
China is now the de facto superpower in this region, and by far the most important trading partner for Vietnam.
During their stay, US sailors will play friendly basketball and soccer matches with locals, hold navy band concerts and visit a center for victims of Agent Orange, the toxic defoliant sprayed over large swathes of land by the USA during the Vietnam War.
The South China Sea is off the coast of Vietnam, and that body of water sees $5 trillion in cargo pass through each year.
The Vietnam War - which Vietnam calls the American War - was protracted and bloody. Some city residents said they welcomed the Navy visit.
China's Foreign Ministry responded to the USS Carl Vinson's visit on Friday by expressing hopes that exchanges between the USA and Vietnam would "contribute to regional peace and stability in a positive and constructive way, instead of adding any unsettling factors".More news: Shkreli Ordered To Forfeit Millions In Assets, Including Rare Albums
"During the war, I was scared when I saw American soldiers", 55-year-old Tran Thi Luyen told the Associated Press. "Now the aircraft carrier comes with a complete different mission, a mission of peace and promoting economic and military cooperation between the two countries".
US carriers frequently ply the South China Sea in a rising pattern of naval deployments, and are now routinely followed by Chinese naval vessels, naval officers in the region say.
Huynh Quang Nguyen, a taxi driver, said he was "happy and excited" about the visit.
But continuing tensions in the South China Sea loom over the trip as Beijing continues to build artificial islands capable of hosting military installations - much to the chagrin of Vietnam and other claimants to the sea. That dread is rooted in China's growing military muscle and regional economic influence as well as the increasingly acquiescent policies of other regional claimant states, namely the Philippines under pro-China President Rodrigo Duterte.
The Carl Vison, which is assigned to the Navy's 3rd Fleet, has been patrolling the Western Pacific after leaving its homeport of San Diego in January.
The United States hasn't taken any official position on South China Sea territorial claims but conducts "freedom of navigation" operations in the waterways by sailing ships without notice through disputed areas. The vessel can carry up to 90 on-deck aircraft. The Ronald Reagan began its Selected Restricted Availability maintenance period in January at Yokosuka Naval Base after completing its fall patrol late a year ago.