In January 2004, McGurk returned to public service as a Legal Advisor to both the Coalition Provisional Authority (CPA) and the United States Ambassador in Baghdad.
During his tenure in Baghdad, McGurk helped draft Iraq's interim constitution, the Transitional Administrative Law, and oversaw the legal transition from the CPA to an Interim Iraqi Government led by Prime Minister Ayad Allawi.
In 2005, he was transferred to the National Security Council, where he served as Director for Iraq, and later as Special Assistant to the President and Senior Director for Iraq and Afghanistan.
In 2006, McGurk became an early advocate for a fundamental change in Iraq policy and helped develop what is now known as "the surge", which began in January 2007.
President Bush later asked McGurk to lead negotiations with Ambassador Ryan Crocker to establish a Strategic Framework Agreement and Security Agreement with the Government of Iraq, thereby ensuring continuity in policy beyond the end of his administration.
In 2009, McGurk was retained during the transition from George W. Bush to Barack Obama, serving as a senior advisor to both the President and the United States Ambassador to Iraq.

McGurk left government service in the fall of 2009 and served as a Resident Fellow at the Harvard Institute of Politics.
He also served as an International Affairs Fellow at the Council on Foreign Relations.
He has also been a frequent commentator on several news outlets.
He was called back into public service in the summer of 2010 after a deadlock over formation of a new Iraqi government, and later in the summer of 2011, following a deadlock in negotiations with the Government of Iraq to extend the Security Agreement that had been concluded in 2008.

In August 2013, he was appointed Deputy Assistant Secretary of State for Iraq and Iran in the Bureau of Near Eastern Affairs at the State Department.

In November 2013, and again in February 2014, McGurk testified before the House Armed Services Committee about the emerging threat of the Islamic State of Iraq and the Levant (ISIL).

On June 9, 2014, McGurk was in Erbil, in the Kurdistan Region of Iraq, when ISIL overran the city of Mosul and approached Baghdad.
He later flew to Baghdad and helped oversee the evacuation of 1,500 U.S. employees from the U.S. Embassy, while working with President Barack Obama and the National Security Council to develop the U.S. diplomatic and military response to the ISIL threat.
McGurk would ultimately play a leading role in facilitating the establishment of a new Government of Iraq, led by Prime Minister Haider Al Abadi, and removing Prime Minister Nouri Al Maliki, who had served as Prime Minister over the past eight years.

On September 12, 2014, Secretary John Kerry announced McGurk's appointment as deputy senior envoy with the rank of ambassador to General John Allen, who that day was named to the newly created position of Special Presidential Envoy for the Global Coalition to Counter ISIL.
On October 23, 2015, Secretary Kerry announced McGurk's appointment as Ambassador and Deputy Special Presidential Envoy for the Global Coalition to Counter ISIL.
Three days later, Ambassador McGurk met in the Oval Office with President Barack Obama and Allen to discuss the strategy for building a global alliance to defeat ISIL.
On December 3, 2014, in Brussels, Belgium, a formal alliance of 62 nations was formed to support Iraq and help the new government under Prime Minister Abadi fight ISIL along five military and diplomatic lines of effort.

In his role as Special Presidential Envoy, McGurk has worked to organize a global coalition of nations as well as coalitions on the ground in Iraq and Syria to help eject ISIL from its strongholds.
He was intimately involved, for example, in negotiating agreements between Arabs and Kurds to prepare for the liberation of Mosul.
He also helped lead negotiations with Turkey to open Incirlik airbase for counter-ISIL missions, and prepare the historic defense of Kobani in Syria by negotiating with Turkey to permit the Kurdish Peshmerga to enter the besieged
In January 2004, McGurk returned to public service as a Legal Advisor to both the Coalition Provisional Authority (CPA) and the United States Ambassador in Baghdad. During his tenure in Baghdad, McGurk helped draft Iraq's interim constitution, the Transitional Administrative Law, and oversaw the legal transition from the CPA to an Interim Iraqi Government led by Prime Minister Ayad Allawi. In 2005, he was transferred to the National Security Council, where he served as Director for Iraq, and later as Special Assistant to the President and Senior Director for Iraq and Afghanistan. In 2006, McGurk became an early advocate for a fundamental change in Iraq policy and helped develop what is now known as "the surge", which began in January 2007. President Bush later asked McGurk to lead negotiations with Ambassador Ryan Crocker to establish a Strategic Framework Agreement and Security Agreement with the Government of Iraq, thereby ensuring continuity in policy beyond the end of his administration. In 2009, McGurk was retained during the transition from George W. Bush to Barack Obama, serving as a senior advisor to both the President and the United States Ambassador to Iraq.
McGurk left government service in the fall of 2009 and served as a Resident Fellow at the Harvard Institute of Politics. He also served as an International Affairs Fellow at the Council on Foreign Relations. He has also been a frequent commentator on several news outlets. He was called back into public service in the summer of 2010 after a deadlock over formation of a new Iraqi government, and later in the summer of 2011, following a deadlock in negotiations with the Government of Iraq to extend the Security Agreement that had been concluded in 2008.
In August 2013, he was appointed Deputy Assistant Secretary of State for Iraq and Iran in the Bureau of Near Eastern Affairs at the State Department.
In November 2013, and again in February 2014, McGurk testified before the House Armed Services Committee about the emerging threat of the Islamic State of Iraq and the Levant (ISIL).
On June 9, 2014, McGurk was in Erbil, in the Kurdistan Region of Iraq, when ISIL overran the city of Mosul and approached Baghdad. He later flew to Baghdad and helped oversee the evacuation of 1,500 U.S. employees from the U.S. Embassy, while working with President Barack Obama and the National Security Council to develop the U.S. diplomatic and military response to the ISIL threat. McGurk would ultimately play a leading role in facilitating the establishment of a new Government of Iraq, led by Prime Minister Haider Al Abadi, and removing Prime Minister Nouri Al Maliki, who had served as Prime Minister over the past eight years.
On September 12, 2014, Secretary John Kerry announced McGurk's appointment as deputy senior envoy with the rank of ambassador to General John Allen, who that day was named to the newly created position of Special Presidential Envoy for the Global Coalition to Counter ISIL. On October 23, 2015, Secretary Kerry announced McGurk's appointment as Ambassador and Deputy Special Presidential Envoy for the Global Coalition to Counter ISIL. Three days later, Ambassador McGurk met in the Oval Office with President Barack Obama and Allen to discuss the strategy for building a global alliance to defeat ISIL. On December 3, 2014, in Brussels, Belgium, a formal alliance of 62 nations was formed to support Iraq and help the new government under Prime Minister Abadi fight ISIL along five military and diplomatic lines of effort.
In his role as Special Presidential Envoy, McGurk has worked to organize a global coalition of nations as well as coalitions on the ground in Iraq and Syria to help eject ISIL from its strongholds. He was intimately involved, for example, in negotiating agreements between Arabs and Kurds to prepare for the liberation of Mosul. He also helped lead negotiations with Turkey to open Incirlik airbase for counter-ISIL missions, and prepare the historic defense of Kobani in Syria by negotiating with Turkey to permit the Kurdish Peshmerga to enter the besieged
Brett McGurk