Mrs. Clinton’s aides said that Myanmar’s government had accommodated the demands of her delegation — which included dozens of officials, security guards and journalists — and imposed no restrictions of her activities. There were logistical challenges that dictated her schedule, including the fact the capital’s airport here was not equipped to handle a landing at night.
In addition to her meetings with government leaders and members of parliament here on Thursday, Mrs. Clinton will travel to Yangon and meet the Nobel Prize-winning opposition leader, Daw Aung San Suu Kyi, at the house where she spent years under arrest as a symbol of quiet but determined resistance to military dictatorship. She plans to also meet with representatives of Myanmar’s long-repressed ethnic minority groups and leaders of nongovernmental organizations.
The decision to send Mrs. Clinton was debated among the White House, the State Department and members of Congress, many of whom remained critical. Representative Ileana Ros-Lehtinen of Florida, the Republican chairwoman of the House Foreign Affairs Committee, said Mrs. Clinton’s trip sent “the wrong signal.”
“Secretary Clinton’s visit represents a monumental overture to an outlaw regime whose D.N.A. remains fundamentally brutal,” Ms. Ros-Lehtinen said in statement Tuesday.
The changes under Mr. Thein Sein over the last eight months have included relaxing restrictions on the news media, politics and business, but not relinquishing the military’s ultimate authority.
Administration officials acknowledge that they do not fully understand how the government makes its decisions and whether the changes are merely superficial or the beginnings of an opening similar to Mikhail S. Gorbachev’s perestroika in the Soviet Union.
The senior administration official said that Mr. Thein Sein, a former general and prime minister, appeared far more open and well-traveled than his predecessor as president, Than Shwe.
“He spent an enormous amount of time traveling outside the country in meetings, interacting with others,” the official said. “And so it’s entirely possible that he had a chance to get a much better sense of what was going on in Southeast Asia, how far behind his country was falling, and what was necessary to take steps to at least address some of the challenges that they were facing going forward.”