The US Secretary of State Hillary Clinton has begun her first substantive talks with Myanmar's new leaders.
Mrs Clinton is the most senior US official in more than half a century to visit Myanmar, also known as Burma.
She told President Thein Sein of the military-backed civilian regime the US is "encouraged" by the steps that the country's new political leaders have taken.
During the talks in the capital, Nay Pyi Taw, the President hailed what he called "a new chapter" in relations with the US.
The United States maintains tight sanctions on senior figures in Myanmar's hierarchy but a series of reforms this year has led to speculation that decades of isolation could be about to end.
However, US officials have stressed there is unlikely to be any major announcements on sanctions during Mrs Clinton's trip.
Analysts say the US is more likely to consider symbolic gestures such as upgrading its mission in Myanmar to a full embassy.
A BBC correspondent in Myanmar says Mrs Clinton will be trying to establish just how much further the new Myanmar leadership is really willing to go.
Mrs Clinton will also travel to the main city of Yangon for a private dinner with the veteran pro-democracy leader Aung San Suu Kyi.
Suu Kyi has said she fully backs Washington's effort to gauge reforms that Myanmar has enacted since the military nominally gave up power to civilian leaders following elections last year.