Aung San Suu Kyi said Tuesday she would not oppose a freeze on US sanctions but urged caution, warning that her country could backtrack after dramatic reforms.

Suu Kyi, who was sworn in May 2 as a member of parliament after spending most of the past two decades under house arrest, spoke via Skype to a rare event in Washington involving former president George W. Bush.

Suu Kyi gave a cautious nod to a call Monday by John McCain, a leading senator of Bush’s Republican Party, for a limited-time freeze on most sanctions on Burma — similar to a recent move by the European Union.

“That is a way of sending a strong message that we will try to help the process of democratization but if this is not maintained, then we will have to think of other ways of making sure that the aspiration of the people of Burma for democracy is respected,” said Suu Kyi.

“I am not against the suspension of sanctions as long as the people of the United States feel that this is the right thing to do at the moment. I do advocate caution, though,” she added.

“I sometimes feel that people are too optimistic about the scene in Burma. You have to remember that the democratization process is not irreversible.”

Repeating one of her frequent themes, Suu Kyi said that reforms would only be considered irreversible once the military — long Burma’s most powerful institution with a history of abuses — firmly committed to changing its ways.

Suu Kyi, the winner of the 1991 Nobel Peace Prize, enjoys wide respect across the political spectrum in Washington and her views are considered critical to any US decision to lift decades worth of sanctions on the country.

Since taking office a year ago, President Thein Sein has surprised even many cynics by opening talks with Suu Kyi and ethnic rebels, allowing by-elections swept by Suu Kyi’s National League for Democracy and freeing political prisoners.

But Suu Kyi said that Burma has not freed 271 political prisoners on a list handed by her party to the home ministry.

“There should be no political prisoners in Burma if we are really heading for democratization,” she said.

McCain, in his proposal to suspend sanctions, said Burma needed to do more to end long-running ethnic wars but that President Thein Sein was “sincere about reform.”

US President Barack Obama’s Democratic administration has championed dialogue with Burma since taking over from Bush but has been cautious about a full lifting of sanctions, saying it needs to preserve leverage to encourage change.

US companies have been eager to enter Burma, fearing Asian and European competitors will seize the growing market. The Obama administration plans to allow limited investment but is fine-tuning the rules, as human rights groups push for strict guidelines.

“The US government should not reward the Burmese government’s nascent and untested changes by allowing an unregulated business bonanza,” John Sifton, Asia advocacy director at Human Rights Watch, said in a statement.

Suu Kyi was speaking at the Washington launch of the Freedom Collection, a project by Bush to bring together lessons from dissidents and reformers.