Obama meets Aung San Suu Kyi
The United States has softened sanctions and removed a ban on most imports from Burma in response to reforms already undertaken, but it has set conditions for the full normalisation of relations, including efforts to end ethnic conflict.
In recent months, sectarian violence between majority Buddhists and the Rohingya Muslim minority in the western state of Rakhine has killed at least 167 people.
Many in Burma consider the Rohingya Muslims to be illegal immigrants from neighbouring Bangladesh and the government does not recognise them as citizens.
A Reuters investigation into the wave of sectarian assaults painted a picture of organised attacks against the Muslim community.
"For too long, the people of this state, including ethnic Rakhine, have faced crushing poverty and persecution. But there's no excuse for violence against innocent people," Mr Obama told a packed audience for a speech at Yangon University.
"The Rohingya ... hold within themselves the same dignity as you do, and I do. National reconciliation will take time, but for the sake of our common humanity, and for the sake of this country's future, it's necessary to stop incitement and to stop violence," he said.
Mr Thein Sein, in a letter to UN secretary general Ban Ki-moon last week, promised to tackle the root causes of the problem, and Mr Obama said he welcomed "the government's commitment to address the issues of injustice, and accountability, and humanitarian access and citizenship".
Some human rights groups had objected to the visit to Burma, saying Mr Obama was rewarding the government of the former pariah state for a job that was incomplete.
Speaking in Thailand on the eve of his visit, Mr Obama denied he was going to offer his "endorsement" or that his trip was premature.
Aides said Mr Obama was determined to "lock in" the democratic changes under way in Burma but would press for further action, including the freeing of all political prisoners.
A senior US official said Mr Obama would announce the resumption of US aid programmes in Burma during his visit, anticipating assistance of $170 million in fiscal 2012 and 2013, but this, too, would be dependent on further reforms.
In a move clearly timed to show goodwill, the authorities began to release dozens more political detainees today, including Myint Aye, arguably the most prominent dissident left in its gulag.
Despite human rights concerns, the White House sees Burma as a legacy-building success story of Mr Obama's policy of seeking engagement with US enemies. In his Rangoon speech, he appealed to North Korea to take a similar path.
"To the leadership of North Korea, I've offered a choice: let go of your nuclear weapons, and choose the path of peace and progress. If you do, you'll find an extended hand from the United States of America," he said.