If he stays in office into 2011, he will be the fifth-longest-serving defence secretary in American history.

'Wilder ideas'

As defence secretary, Gates has managed the wind-down of the war in Iraq and a changing Pentagon whose budget he aims to trim.

He has also overseen the war in Afghanistan and Obama's surge of some 30,000 military personnel, who will finish arriving this year even as the United States promises to begin withdrawing from the country in July 2011.

  Video: Al Jazeera Interviews Robert Gates
  Profile: Robert Gates

"What you saw with Robert Gates, particularly ... under Barack Obama, was someone who was able to take some of his wilder ideas for transforming the way the defence department does its job and actually start putting into play some of those ideas," Al Jazeera's Rosalind Jordan, reporting from Washington DC, said.

In 2009, Gates and a team of reviewers decided to eliminate, defund or restructure 33 programmes within the defence department, according to the Foreign Policy article.

Among the more controversial was Gates' decision to halt the production of the F-22 Raptor stealth fighter plane, a darling of the Air Force that would have cost the US tens of billions of dollars over the coming years.

"The question is whether someone who follows [Gates] can see that process through", Jordan said.

Afghan review

In the Foreign Policy interview, Gates noted that the Obama administration's upcoming assessment of its strategy in Afghanistan will be complete by the end of December.

"The point ... is I think that by next year I'll be in a position where, you know, we're going to know whether the strategy is working in Afghanistan. We'll have completed the surge. We'll have done the assessment in December. And it seems like somewhere there in 2011 is a logical opportunity to hand off", he said, according to a transcriptposted on the magazine's website.

Gates also said he fears it will be harder to find an adequate replacement for himself in 2012, as the Obama White House gears up for a likely re-election campaign.

"I think we might have trouble getting the kind of person they want if there's a possibility that they might only be in the job for a year", he said, referencing the chance that Obama could lose an election.

"You know, who knows what the election situation will look like. But also I just think this is not the kind of job you want to fill in the spring of a presidential election. So I think sometime in 2011 sounds pretty good".

Successor speculation

In another post on Foreign Policy's website,reporter Josh Rogin listed some notables in the American capital rumoured to be possible choices should Obama need to replace Gates.

They include Michèle Flournoy, the undersecretary of defence for policy, John Hamre, the president of the Centre for Strategic and International Studies, Leon Panetta, the director of the Central Intelligence Agency, and Richard Danzig, a former secretary of the navy.