President Xi is conquering Vietnam with kindness on a two-day mission to Hanoi that’s intended to show Communist China is Vietnam’s greatest friend three months after President Biden played the same game in a bid to draw Vietnam out of China’s orbit.

Vietnam has pulled out all the stops in bowing before the leader of the big brother country that armed Hanoi’s soldiers against America and South Vietnam more than 48 years ago but then turned against the Vietnamese in a fierce border war less than four years later.

When it comes to pomp and circumstance, Mr. Xi scored a 21-gun salute when he was greeted by his opposite number, the general secretary of Vietnam’s Workers party, Nguyen Phu Trong.  

Mr. Biden, when he was in Hanoi in September, got to watch  as soldiers high-stepped to the tune of the Vietnam and American national anthems before he and his Vietnam host elevated the American-Vietnam relationship to “comprehensive strategic partnership” — the same level as that between Vietnam and China.

Could it have been that the sound of Vietnamese cannon booming away during Mr. Biden’s visit might have seemed inappropriate considering the memories of the long Vietnam War? In any case, Vietnam’s reception for Mr. Xi was more elaborate than the lavish-enough welcome accorded Mr. Biden when he dropped by for a day in the midst of an Asia swing.

The reason, no doubt, is that China and Vietnam not only share a border of more than 800 miles but also a history marked by war and peace, conquest and revolt, going back 2,000 years. On Tuesday, the mood was upbeat despite Vietnam’s demand, not so far stated publicly during Mr. Xi’s visit, that China stop encroaching on its drilling rights in the South China Sea and return an island cluster known as the Paracels.

A Vietnam National University faculty member, Nguyen Tang Nghi, summarized the importance of the visit, telling the state-controlled press that the visit, Mr. Xi’s first to Vietnam in six years, “proves that Vietnam’s position has been elevated and the country has truly become a political, economic, and security center of the region.”

The Chinese mouthpiece, the English-language Global Times, left no doubt that the visit was intended to counter America’s inroads in a country that would obviously prefer to play Beijing’s interests against those of Washington. Yet what does Vietnam hope to gain from Mr. Xi and vice versa?

“Vietnam and China are expected to sign dozens of important cooperation agreements on multiple fields, including security and defense, communications, trade, investment, digital economy, agriculture export, green development and maritime cooperation,” said the Vietnam Express.

One dividend could be an upgrade in rail service between the two countries — a high-speed link in place of the cumbersome arrangement by which passengers now have to change trains at the border. 

Who knows? Perhaps the Chinese could turn the historic but decrepit line between Hanoi and Ho Chi Minh City, still known widely as Saigon, the heart of  what was known in the old days as “South Vietnam,” into a really fun ride.

All that would fit right in with China’s controversial “belt and road initiative” under which China is extending the tentacles of its influence from Southeast Asia to the Middle East and even Europe while Washington competes with its Indo-Pacific strategy.

One way Washington has much more to offer: Vietnam has a trade surplus of more than $100 billion with America this year while China enjoys a surplus of more than $60 billion from trade with Vietnam. The Vietnamese make their biggest profit from export of electronic items; China profits from export of manufactured products.

Carl Robinson, an old-time Australian journalist who still visits Vietnam regularly and often writes about the country, sees Vietnam as playing the game both ways. Looking at Mr. Xi’s visit somewhat skeptically, he remarked, “Overall, the usual bending with the wind stuff for the Vietnamese.”