The president of Myanmar, a former general who has led the move away from a prolonged era of dictatorship, poverty and isolation, asserted on Thursday in his first United Nations speech that “amazing changes” were transforming his country and could never be reversed.

The president, U Thein Sein, also paid homage to the country’s opposition leader, Daw Aung San Suu Kyi, a Nobel Peace Prize winner and former political prisoner whose liberation from nearly two decades of house arrest in 2010 signaled the beginning of Myanmar’s gradual emergence from pariah status.

“As a Myanmar citizen, I would like to congratulate her for the honors she has received in this country in recognition of her efforts for democracy,”said Mr. Thein Sein in his address to the United Nations General Assembly.

It was the first time that Mr. Thein Sein had praised Ms. Aung San Suu Kyi in such a public way, and appeared to reflect growing confidence that his navigation of Myanmar’s political system away from decades of authoritarian rule would not be challenged at home, where many of his colleagues in the military are known to be ambivalent about the changes.