Jeremy B. Bash was the chief of staff at the U.S. Department of Defense (2011–2013) and the Central Intelligence Agency (2009–2011).
 As a senior advisor to Leon Panetta in both roles, Bash worked on a number of key initiatives, including the creation of a new defense strategy, formation of two defense budgets, counterterrorism operations, a new cyber strategy, and a range of sensitive intelligence operations.
Robert Orton Work (born January 17, 1953) is a United States national security professional who served as the 32nd United States Deputy Secretary of Defense for both the Obama and Trump administrations from 2014 to 2017.
 Prior to that, Work was the United States Under Secretary of the Navy from 2009 to 2013, and before that served as a Colonel in the United States Marine Corps; Work retired in 2001 and worked as a civilian at the Center for Strategic and Budgetary Assessments (CSBA) and the George Washington University in various positions relating to military and strategic study.
 From 2013 to 2014, he was the CEO of the Center for a New American Security (CNAS).
The Panetta Review was a secret internal review conducted by Leon Panetta, then the Director of the United States Central Intelligence Agency, of the CIA's torture of detainees during the administration of George W. Bush.
 The review led to a series of memoranda that, as of March 2014, remained classified.
 According to "The New York Times", the memoranda "cast a particularly harsh light" on the Bush-era interrogation program, and people who have read them have said parts of the memos are "particularly scorching" of techniques such as waterboarding, which the memos describe as providing little valuable intelligence.
The Center for a New American Security (CNAS) is a Washington, D.C.-based think tank established in 2007 by co-founders Michèle Flournoy and Kurt M. Campbell.
 It specializes in the United States' national security issues.
 CNAS's stated mission is to "develop strong, pragmatic and principled national security and defense policies that promote and protect American interests and values."
 CNAS focuses on terrorism and irregular warfare, the future of the U.S. military, the emergence of Asia as a global power center, and the national security implications of natural resource consumption.
 Former Deputy Secretary of State James Steinberg called CNAS "an indispensable feature on the Washington landscape."
 Speaking at the CNAS annual conference in June 2009, U.S. Central Command Commander GEN David Petraeus observed that "CNAS has, in a few years, established itself as a true force in think tank and policy-making circles."
Michèle Angelique Flournoy (born December 14, 1960) is the former Under Secretary of Defense for Policy, the seventh-ranking official in the U.S. Department of Defense, and in that role served as a principal advisor to U.S. Secretaries of Defense Robert Gates and Leon Panetta from February 2009 to February 2012.
 When the U.S. Senate confirmed her nomination on February 9, 2009, she was at the time the highest-ranking woman at the Pentagon in the department's history.
James Varni Panetta (born October 1, 1969) is an American politician from the state of California.
 He is a member of the United States House of Representatives for California's 20th congressional district.
 He is the son of Leon Panetta, who represented the Monterey area in Congress for 16 years before holding such jobs as White House Chief of Staff and Secretary of Defense.
Leon Edward Panetta (born June 28, 1938) is an American politician who has served in several different public office positions, such as Secretary of Defense, Director of the CIA, White House Chief of Staff, Director of the Office of Management and Budget, and as a U.S. Representative from California.
 A Democrat, Panetta was a member of the United States House of Representatives from 1977 to 1993, served as Director of the Office of Management and Budget from 1993 to 1994, and as President Bill Clinton's Chief of Staff from 1994 to 1997.
 He co-founded the Panetta Institute for Public Policy and served as a Distinguished Scholar to Chancellor Charles B. Reed of the California State University System and as a professor of public policy at Santa Clara University.
Elissa Slotkin is the former Acting Assistant Secretary of Defense for International Security Affairs under the Obama Administration.
 She was the principal advisor to the Under Secretary of Defense and Secretary of Defense on security strategy and policy issues related to the nations and international organizations of Europe (including the North Atlantic Treaty Organization), Russia, the Middle East, Africa, and the Western Hemisphere.
 She also had oversight for security cooperation programs, including foreign military sales in these regions.
 Previously, from September 2012 to January 2015, Elissa served as Principal Deputy Assistant Secretary of Defense for International Security Affairs.
 From July 2013 to August 2014, she performed the duties of Principal Deputy Under Secretary of Defense for Policy.
Bradley M. Berkson (born February 26, 1963) was the last United States Department of Defense Director, Program Analysis and Evaluation, a position retitled Director of Cost Assessment and Program Evaluation.
 Berkson also served as the Acting Deputy Under Secretary of Defense for Logistics and Materiel Readiness now termed Assistant Secretary of Defense for Logistics and Materiel Readiness.
 Berkson led Secretary of Defense Robert Gates' Intelligence, Surveillance, & Reconnaissance (ISR) Task Force.
 Berkson served in the Bush Administration and remained in the Obama Administration until April, 2009.
Derek Chollet is Executive Vice President for security and defense policy at the German Marshall Fund of the United States, and author of the book, "The Long Game: How Obama Defied Washington and Redefined America's Role in the World " (Public Affairs, 2016).
 He is a contributing editor to Foreign Policy, where he coedits "Shadow Government," and is a regular contributor to Defense One, is also an advisor to Beacon Global Strategies and an Adjunct Senior Research Scholar at Columbia University’s Saltzman Institute of War and Peace Studies.
 From 2012-2015, Mr. Chollet was the U.S. Assistant Secretary of Defense for International Security Affairs, where he managed U.S. defense policy toward Europe (including NATO), the Middle East, Africa, and the Western Hemisphere.
 In that role, he was a senior advisor to two secretaries of defense, Leon Panetta (July 2011 until February 2013) and Chuck Hagel (until February 2015).

Question: Which cofounder of the Center for a New American Security served as a principal advisor to U.S. Secretaries of Defense Robert Gates and Leon Panetta?
Answer: Michèle Flournoy