General David Petraeus, one of the United States' most prominent military officers, has indicated he would be willing to serve in President-elect Donald Trump's administration if asked.
Speaking to BBC Radio 4's Today programme, he said: "The only response can be: 'yes, Mr President'."
Gen Petraeus resigned as CIA director in 2012 following an extramarital affair with his biographer.
It later emerged he had shared classified material with her.
He served as a senior officer under Presidents Bush and Obama. He was the commander of US and Nato forces in Afghanistan, before retiring from the military to take the top position in the Central Intelligence Agency.
Asked if he thought Mr Trump had the correct temperament to be the US President, he said: "It's up to Americans at this point in time not only to hope that that is the case, but if they can, endeavour to help him."
He then indicated he would personally serve under Mr Trump if asked.
"If you're asked, you've got to serve - put aside any reservations based on campaign rhetoric... and figure out what's best for the country," he said.
"I've been in a position before where a president has turned to me in the Oval Office in a difficult moment, without any pleasantries, and said 'I'm asking you as your president and Commander in Chief to take command of the international security force in Afghanistan.'
"The only response can be: 'yes, Mr President,'" he continued.
A number of media outlets have linked the retired general with positions in the new administration.
A report in The Guardian last week linked Gen Petraeus to the race for secretary of state, citing diplomatic sources.
Mr Trump has been putting together his administration made up of friends, family, and former rivals - but several key positions, including secretary of state, remain open.
General Petraeus was indirectly critical of some of Donald Trump's rhetoric during the presidential election campaign, describing the president elect's anti-Muslim comments as toxic.
However, he said he had heard good things from those who have been speaking with Mr Trump since the election result.
"It's interesting that those who have been talking to him have said, you know, he's very personable, very hospitable, very gracious guy, full of questions and dialogue," he said.
He also suggested that Mr Trump could forge closer ties with Russia, comparing his political position to that of President Nixon's overtures to China in the 1970s.
"Only Nixon could have gone to China. Anyone else would have been criticised from the right," he said.
"I think that the current president would have been criticised from the right had he tried some of the kinds of outreach that, in fact, President-elect Trump may pursue."
But he warned that any such outreach should be attempted "with your eyes wide open".