In September 2001, Zalmay Khalilzad, now the U.S. ambassador to Iraq and a key player in the country's democratic process, was working as an obscure staffer in the National Security Council.

But as the Bush administration's war on terror unfolded after 9/11, Khalilzad, an Afghan-born Muslim with a background in Middle East policy, rose to a prominent role as an adviser, intermediary and policymaker. He was appointed as a special presidential envoy to Afghanistan following the U.S.-led invasion to oust the Taliban, and in 2003, Khalilzad became U.S. ambassador to Afghanistan.

He helped acting Afghan President Hamid Karzai set up a transitional government in the country of his birth and oversaw its first democratic elections in late 2004.

President Bush appointed Khalilzad to replace John Negroponte as U.S. ambassador to Iraq in June 2005 where his first task was negotiating a compromise between the Kurds, Shiites, Sunnis and secular groups over the constitution. He paid special attention to bringing Sunnis into the political process, especially after a coalition of Shiite parties won the most in parliamentary elections held in December 2005.

"The fundamental problem of Iraq is that the various communities are polarized along ethic and sectarian lines," Khalilzad told the NewsHour in February 2006. "And to deal with this problem, they need to form a national unity government, and that's what we are encouraging."

Khalilzad earned a reputation as a strategic thinker and one who can balance the complexity of politics in the Middle East with U.S. policy.

"He brings a lot more to bear than his predecessors, who knew nothing about Iraq. I wonder how many of our top decision-makers knew, a few years ago, the difference between Sunni and Shia," said Zbigniew Brzezinski, national security adviser for President Jimmy Carter, in an interview with The New Yorker. "He is a broad-minded pragmatist and an insightful strategist. He has a unique advantage in a part of the world in which the United States has become massively engaged and does not have many people at the top equipped to deal with it."

In Iraq, Khalilzad lives in the Baghdad's Green Zone and travels in a security convoy often backed up with armed helicopters for air support. He works from his office in Saddam Hussein's former marble presidential palace supervising a staff of 5,000, the largest U.S. Embassy in the world.

Khalilzad was born in 1951 in Mazar-i-Sharif in northern Afghanistan. His father worked in the local office of the ministry of finance. His mother, though illiterate, kept informed by having her children read the newspapers out loud to her.

His family moved to Kabul when he was in eighth grade. In high school he spent a year as an exchange student in California that he credits with giving him a different approach to his home country.

Khalilzad went on to attend Kabul University but transferred to the American University of Beirut after winning a scholarship. He studied political science and history of the Middle East in Beirut from 1970 to 1974. During this time, he met his wife Cheryl Bernard who was researching a dissertation on Arab nationalism. The couple has two sons.

In 1975, Khalilzad came to American to pursue his doctorate at the University of Chicago under the guidance of Albert Wohlstetter, an expert in military strategy who helped him make contacts in Washington. Wohlstetter exposed Khalilzad to the so-called neoconservative approach to foreign policy that places an emphasis on using America's military power.

Khalilzad accepted a teaching position in the political science department at Columbia in 1979 and wrote articles about the Soviet Union's invasion into Afghanistan that received considerable attention from experts. In 1984 he became an American citizen and accepted a fellowship with the Council on Foreign Relations.

From 1985-89, Khalilzad served as an adviser on Afghanistan and the Iran-Iraq war at the State Department where he wrote a policy paper that called for the U.S. to shift its focus from Iraq to Iran. He left the government for the Rand Corporation, a nonprofit research organization where he founded the Center for Middle Eastern Studies.

During the first Persian Gulf war, Khalilzad worked for the Defense Department as the assistant deputy undersecretary for policy where he received the Department of Defense medal for outstanding public service.

Convinced that the United States had left unfinished business after driving Iraq from Kuwait, Khalilzad encouraged then-Secretary of Defense Dick Cheney to remove Saddam Hussein from power and continued to push for regime change in Iraq.

After the war, he was assigned to analyze America's strategic position in the post-Cold War world and helped draft the Defense Planning Guidance of 1992 that outlined a strategy for maintaining America's global hegemony using the threat of military force.

When George W. Bush was elected in 2000, Khalilzad headed the Bush-Cheney transition team at the Pentagon and was a counselor to Secretary of Defense Donald Rumsfeld. In 2001, he moved to the National Security Council to become the Special Assistant to the President and Senior Director for Southwest Asia, Near East and North African Affairs.

-- Compiled by Anna Shoup for the Online NewsHour