US president Barack Obama has said he may speak out after leaving office if he feels his successor Donald Trump is threatening core American values.
By convention, former presidents tend to leave the political fray and avoid commenting on their successors.
Speaking at a news conference at the Apec summit in Lima, Peru, Mr Obama said he intended to assist Mr Trump and give him time to outline his vision.
But he said that, as a private citizen, he might speak out on certain issues.
"I want to be respectful of the office and give the president-elect an opportunity to put forward his platform and his arguments without somebody popping off," Mr Obama said.
But, he added, if an issue "goes to core questions about our values and our ideals, and if I think that it's necessary or helpful for me to defend those ideals, then I'll examine it when it comes".
The president described himself as an "American citizen who cares deeply about our country".