HANOI, Vietnam — When Bill Clinton landed in this lake-studded capital 16 years ago, the first American president to visit since the end of the Vietnam War, his mission was to put that conflict behind him, and the trip was among the most remarkable of his presidency.
When President Obama arrives here early Monday, his task may be a bit less dramatic, but is in many ways far more ambitious. These two countries, bedeviled by decades of misunderstandings, violence and wariness, now have the chance to create a partnership that seemed unlikely even three years ago.
Since then, China’s expansion in the South China Sea has deeply shaken a new Vietnamese government. While the leadership here has not let up on its repression of its people — the police have beaten protesters in demonstrations over an environmental disaster — it now appears more interested in playing one superpower off against the other, perhaps even giving the Pentagon some rotating access to key Vietnamese ports.
It would not be an alliance; neither side seems ready for that. But it could throw Beijing off balance in the daily shadowboxing over who will dominate one of the world’s most strategically vital waterways.
“It does show how history can work in unpredictable ways,” said Benjamin J. Rhodes, a deputy national security adviser who spent time over the past two years luring Myanmar out of its shell. “Even the worst conflicts can be relatively quickly left behind.”
In many parts of Asia, Mr. Obama’s strategy of focusing on the region is still more of a slogan than an operational plan. He has been drawn back into Middle East conflicts in Iraq, Syria and Yemen. But in this part of Southeast Asia, particularly Vietnam, he seems on the verge of the kind of progress Mr. Clinton could only imagine during that first visit, only 10 months before the Sept. 11 attacks changed America’s priorities.
Slurping noodles in a shop in Ho Chi Minh City at the end of that trip, Mr. Clinton wondered aloud to a reporter whether the Communist leaders in Vietnam were really willing to turn away from their traditional link to China. It turned out they were not.
But now the Chinese, who hindered American efforts during the Vietnam War, are making things easier for the United States. For years, the Communist Party leadership in Vietnam, headed by Nguyen Phu Trong, ignored Chinese activity off the country’s coast even as its deeply nationalistic population became increasingly alarmed. But in 2014, China placed a deep-sea drilling rig to explore for oil and gas right off Vietnam, and Mr. Trong, the party’s general secretary, could not even get his phone calls to Beijing returned.
He registered his protest by visiting Mr. Obama in the Oval Office last year, an unsubtle signal to the Chinese that Vietnam had other options. But with a military leadership still full of veterans of the American War, as it is known here, the warming of ties has proceeded at a deliberate pace.
Ahead of Mr. Obama’s visit, a parade of American officials, including Deputy Secretary of State Antony Blinken and Daniel Russel, the State Department’s most senior Asia hand, have been showing up in Hanoi. Their goal has been to get enough human rights guarantees from the Vietnamese to allow for the lifting of sanctions on arms sales to Vietnam and perhaps the return of American military units to its shores for the first time since the chaotic helicopter evacuation from Saigon that is seared in the American memory.
For most Vietnamese, half of whom are under 30, Internet-armed and increasingly savvy about the world around them, those memories have little meaning to their lives or ambitions. Poll after poll shows that improved ties with the United States are highly sought.
And they demonstrated their power when they took to the streets in recent weeks over a huge fish kill, believed to have resulted from a spill by a Taiwanese-owned steel plant. The government crackdown that followed was not exactly part of the game plan before Mr. Obama’s arrival.
Mr. Obama is making his first visit late in his presidency; he has already been to Myanmar twice. But unlike Mr. Clinton and President George W. Bush, he arrives without the burden of having to explain what he was doing during the war; by the time he turned 18, Saigon, now Ho Chi Minh City, had fallen.
For Mr. Obama, the trip has its political sensitivities. On the campaign trail, Republicans will almost certainly cast it as another stop on an eight-year-long “apology tour.” During his visit in November 2006, Mr. Bush avoided any notion of an apology in part by avoiding most Vietnamese. His attention was focused on the Iraq war, then in its worst phase, and the trip was overshadowed by questions of whether the United States was entering another quagmire. (“We’ll succeed unless we quit,” Mr. Bush said when pressed on the comparisons.)
Mr. Obama has made clear that pragmatism outweighs other factors when it comes to maneuvering around Beijing. From a practical viewpoint, a decision to lift the arms embargo against Vietnam would have minimal effects — the Vietnamese military still likes Russia’s rock-bottom prices for arms — but it would be symbolically important.
“The delicate balance is that we need to have both a constructive relationship with China and the ability to be firm on some issues,” Mr. Rhodes said in an interview.
Then there is the question of the reception Mr. Obama will receive. He is more popular here and in Europe than he is at home. His aides are clearly hoping for a welcome more like the one Mr. Clinton received in November 2000. Mr. Clinton spoke to students, took in the sights, went shopping and spent hours in a rice field outside Hanoi, sifting the dirt for the remains of a downed American pilot alongside the pilot’s sons, who had accompanied the president.
Mr. Obama’s schedule is very light on the war, and very focused on the future. After meetings on Monday with the country’s leadership, he will spend Tuesday with dissidents and then deliver a speech. Then he will head to Ho Chi Minh City, landing at the airport that was once the hub of the American military effort, and will meet with entrepreneurs.
On Wednesday, Mr. Obama will hold a forum with members of the Young Southeast Asian Leaders Initiative, a signature effort of his to strengthen ties with a remarkably young population throughout the region.
An earlier version of this article gave an incorrect location for a reporter. David E. Sanger reported from Naypyidaw, Myanmar, not Washington.