Barack Obama is to shake up his national security team and remake his defence and foreign policy on Thursday, with General David Petraeus moving from Afghanistan to head the CIA and Leon Panetta leaving the agency to become defence secretary.
The White House confirmed that Obama would announce details of the first major reshuffle of his administration but refused to go into details.
The changes will have implications for the war in Afghanistan and, more generally, for the bloated defence budget. They will also influence the Obama administration's approach to the uprisings throughout the Middle East.
The reshuffle will end the formidable partnership between Robert Gates, the present defence secretary, and Hillary Clinton, the secretary of state, that has dictated foreign policy for most of the last two years. Clinton is staying but Gates, whom Obama inherited from the Bush administration, is to retire.
The reshuffle, due to take place in July, comes at a critical point in the Afghanistan war. Obama agreed to a Pentagon request to send 30,000 more US troops to Afghanistan but, in a rare battle with military chiefs, insisted that their withdrawal begins in July.
But Petraeus, seeing events on the ground as fragile, is reluctant to begin withdrawing anything more than a few thousand. He is due to report on this to Obama in Washington this week. The president, with an election to fight next year, is seeking a significant reduction in the 100,000 US troops there.
Petraeus was rushed to Afghanistan last summer after Obama sacked the US commander, Stanley McChrystal. Petraeus was scheduled to leave at the end of this year, but the reshuffle brings his departure forward.
Petraeus insists that the US and allied forces have made significant gains over the winter but adds that these are fragile and should not be endangered by pulling out too many troops too soon.
After a meeting to discuss Afghanistan this week, the White House spokesman, Jay Carney, said: "The president's policy, beginning of a drawdown of American troops, is absolutely still on track."
Asked about the reshuffle, Carney said: "The president will be addressing these questions about personnel tomorrow."
Panetta's move to defence is also significant. Gates, popular at the defence department, implemented some budget cuts but Obama is looking for much more in a time of austerity. Panetta, a Democrat, has a background as a budget cutter.
The new defence secretary may also prove tougher in taking on the Pentagon and members of Congress with a vested interest in expensive military projects.
Associated Press, which broke the news of the reshuffle, also reported that Lieutenant-General John Allen would replace Petraeus as the Afghanistan commander and Ryan Crocker, a veteran diplomat, would be the next US ambassador in Afghanistan.
All four of the new team are expected to stand alongside Obama at the White House when the president makes the announcement.
The Obama administration has been criticised for inconsistency in its response to the Arab spring, sending US planes and Predator drones to attack the forces of the Libyan leader, Muammar Gaddafi, but taking little action other than planned new sanctions against the Syrian president, Bashar al-Assad.
One of the rare divisions between Gates and Clinton was in response to Libya, with Clinton eventually coming round in favour of intervention and Gates remaining strongly opposed, arguing that the US was already sufficiently committed and could not intervene everywhere.
The reshuffle could see a different emphasis in US policy in Afghanistan, with a tilt more towards political solutions. While Gates and Petraeus have stressed the need to inflict defeats on the Taliban on the battlefield before entering into political discussions with them, others have been pressing for more back-channel discussions.
Petraeus had been hoping to leave Afghanistan to take the top military job, chairman of the joint chiefs of staff, at present occupied by Admiral Mike Mullen, who is planning to resign later this year. But the CIA job may suit him better in the long run.
There is widespread speculation that he would like to stand as Republican candidate in the 2016 White House race and the combination of senior military commander and director of the CIA would given him a solid campaign platform. He would be the highest-ranking military figure to become president since Eisenhower in the 1950s.
Panetta has extensive experience in cutting budgets and the Pentagon is a prime candidate, with investment in a lot of hi-tech hardware that could be used in conventional warfare but is of little use in the kind of insurgencies the US is engaged in in Afghanistan and elsewhere.
He was director of the White House office of management and budget. Gates has managed to cut a planned $400bn (£240bn) from the defence budget over the next decade but the Obama administration wants double that.
Panetta, who was chief of staff in the Clinton administration between 1994 and 1997, was initially viewed with suspicion by the CIA because of his lack of intelligence experience. Former CIA officers say he has won over the intelligence agency, battling for it on a series of difficult and embarrassing issues.
The present US ambassador to Afghanistan, Karl Eikenberry, has had an unhappy time in Kabul, with a public spat with the late US special envoy, Richard Holbrooke, and other rows.
Both Panetta and Petraeus would have to go in front of Senate committees to be confirmed. This can be gruelling and many candidates have been blocked at this stage in the past.
But, judging by past performances at Senate hearings, both are popular with senators and should go through relatively easily. Leaving the appointments until the summer allows time for the Senate hearings.