President Donald Trump has removed his senior strategist Steve Bannon from the US National Security Council (NSC).
The appointment in January raised fears that the circle of US intelligence chiefs was being politicised.
A White House aide said the reshuffle was not a demotion for Mr Bannon, who used to head up Breitbart News.
The aide said Mr Bannon was only given a seat on the NSC to keep an eye on National Security Adviser Michael Flynn, who was fired in February.
The NSC is the main group advising the president on national security and foreign affairs.
Palace intrigue - Anthony Zurcher, BBC News, Washington
Another day, another bit of palace intrigue in the White House. After a week in which presidential son-in-law Jared Kushner's power seemed to grow exponentially, another longtime Trump insider, Steve Bannon, has had his wings clipped.
The White House attempted to brush off news that the senior political adviser is no long a principal on the National Security Council, but the on-background administration explanations ring hollow.
Was Mr Bannon really just there to "de-operationalise" the council after the Obama years or, even more improbably, keep an eye on former National Security Adviser Michael Flynn? In January, White House Press Secretary Sean Spicer vigorously asserted that Mr Bannon's presence on the council was nothing out of the ordinary.
Washington foreign policy insiders are probably relieved by this development, as they largely considered Mr Bannon a reckless and inexperienced provocateur. They may believe that international affairs "grown-ups" are finally in control.
Although his national security influence may have been curtailed, Mr Bannon will continue to cast a long shadow in this administration. He occupies prime White House real estate, reportedly maintains his top security clearance and, most importantly, almost certainly still has the president's ear on political matters.
The White House did not announce Wednesday's presidential executive order detailing the shake-up - it only came to light in a regulatory filing.
The reshuffle also restores the director of national intelligence, CIA director and chairman of the Joint Chiefs of Staff to full participation on the NSC's inner circle, its principals committee.
Critics have branded Mr Bannon - who once managed populist, right-wing Breitbart News - as a white nationalist.
In its 27 January memorandum elevating Mr Bannon, the White House had also downgraded the military chiefs of staff, provoking widespread criticism in Washington's foreign policy and security establishment.
The director of national intelligence and the joint chiefs were advised they only needed to attend NSC meetings when discussions pertained to their areas.
The White House bridled in January at criticism of the Bannon move, pointing out that President Barack Obama's former adviser, David Axelrod, regularly attended NSC meetings.
However, Mr Axelrod was never appointed to the principals committee, as Mr Bannon was.