The White House has named veteran diplomat and ex-State Department official Paul Bremer as the man whose task it is to supervise the transition to democracy in Iraq.
Mr Bremer will be the top civilian official in the country, outranking the retired General Jay Garner, who had been appointed Iraq's chief civil administrator.
The 61-year-old former foreign service officer will oversee all political and reconstruction efforts in Iraq.
Bremer: A "can do" type
The shift to Mr Bremer from Mr Garner puts a State Department person above a Pentagon appointee, although the former is known as someone who is close to US Defence Secretary Donald Rumsfeld. Mr Bremer will report directly to the Pentagon chief.
Mr Bremer has been described by Mr Rumsfeld as a "friend and an enormously talented person".
BBC correspondents say the aim is for Mr Bremer to broker a truce between the State and Defence Departments, which have presented rival agendas for running Iraq.
Announcing his appointment, President George W Bush described him as a "can-do" person.
One of his key tasks will be to decide which Iraqis join the interim administration.
Before his retirement in 1989, Mr Bremer served for 23 years in the State Department. He held a variety of senior posts, including top aide for six secretaries of state.
His foreign service career has included stints in Malawi, Norway, the Netherlands and Afghanistan but never in the Middle East.
He has a reputation for being tough. Former colleagues at the State Department say he is known for being blunt and decisive, and is always ready to take a stand.
Mr Bremer is the State Department's former head of counter-terrorism. He was made ambassador-at-large for counter-terrorism in 1986 by President Reagan.
He retired three years later but returned to the public eye in 1999 when he was named co-chair on the National Commission on Terrorism. The body produced a report in the summer of 2000 reviewing US counter-terrorism policy.
According to newspaper reports, this role made him something of a voice of doom. In 2000, he warned in congressional testimony of possible terror attacks, such as a radioactive release that "made 10 miles of Chicago's waterfront uninhabitable for 50 years".
At one point, he also publicly urged President Clinton to confront terrorism and the so-called rogue states of Syria, Iran and Sudan more aggressively.
After retiring from the State Department he entered the world of business, helping to run former Secretary of State Henry Kissinger's consulting firm Kissinger Associates.
Most recently, he has been running a consulting firm advising on risk management around the world.