President Barack Obama on Tuesday pressed Vietnam to allow greater freedoms for its citizens, arguing that better human rights would improve the communist country's economy, stability and regional power.

On his second full day in Vietnam, Obama met with activists and entrepreneurs, part of a push for closer ties with the fast-growing, strategically crucial country that included the lifting of one of the last vestiges of Vietnam War-era antagonism: a five-decades-old arms sale embargo.

In a speech at the National Convention Center, Obama sought to ease fears that Washington wanted to dictate terms to Vietnam on improving rights. He has faced calls by activists to more strongly address what's seen as an abysmal treatment of government critics.

Nations are more successful when people can freely express their thoughts, assemble without harassment and access the internet and social media, Obama said.

"Upholding these rights is not a threat to stability but actually reinforces stability and is the foundation of progress," Obama said. "Vietnam will do it differently than the United States ... But there are these basic principles that I think we all have to try to work on and improve."

Obama earlier spoke with six activists, including advocates for the disabled, sexual minorities, a pastor and advocates for freedom of speech, press and the Internet, but he said that several others were prevented from coming.

"Vietnam has made remarkable strides in many ways," Obama said, but "there are still areas of significant concern."

Obama must balance a desire for a stronger relationship with efforts to hold its communist leadership to account over what activists say is the widespread abuse of dissidents.

From Hanoi, Obama was to fly Tuesday to Ho Chi Minh City, formerly Saigon. He planned a visit to the Jade Pagoda, considered one of the most beautiful pagodas in southern Vietnam and a repository of religious documents that includes more than 300 statues and other relics.

Shifting from the historical to the modern, Obama also planned to visit the Dreamplex business complex in downtown Ho Chi Minh City, a space for startup entrepreneurs that fits with Obama's message about the potential benefits of closer ties to Vietnam's growing economy and its burgeoning middle class.

Obama also planned to meet with entrepreneurs, letting him talk up the benefits of what he says will be enhanced trade under a 12-nation trans-Pacific trade deal that is stalled in Congress and opposed by the leading U.S. presidential candidates. Obama said the U.S. was ready to help Vietnam meet its commitments under the agreement. He said during his address that the agreement would give workers the right to form unions and prohibits forced labor and child labor. He also predicted the pact, if ratified, would lead to greater regional cooperation.

During a Monday news conference with Vietnam's president, Obama traced the arc of the U.S.-Vietnamese relationship through cooperation, conflict, "painful separation" and a long reconciliation. "If you consider where we have been and where we are now, the transformation in the relations between our two countries is remarkable," Obama said.

Activists, however, said the president had given up his best leverage for pressing Vietnam to improve its rights record by lifting the arms embargo.

Vietnam holds about 100 political prisoners and there have been more detentions this year, some in the past week. Hanoi says that only lawbreakers are punished.

Obama said there had been "modest progress on some of the areas that we've identified as a concern." He added that the 12-nation trans-Pacific trade deal that he's pushing could help prompt Vietnam to implement a series of labor reforms "that could end up being extraordinarily significant."

For Vietnam, lifting the arms embargo was a psychological boost.

The United States partially lifted the ban in 2014, but Vietnam has repeatedly pushed for full access so it can better deal with China's land reclamation and military construction in nearby seas.