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Marik A. String

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Marik A. String

Partner

Washington DC + 1 202 663 6732

Marik A. String is a partner in the Defense, National Security and Government Contracts group, based in the Washington DC office. He counsels clients on sanctions and national security regulatory issues; global investigations and compliance; and international, investor-state and sovereign-related disputes. A globally-recognized leader in international and national security law, he returned to the firm in 2025 after serving 16 years in senior US government roles at the Department of State, Department of Defense and US Senate, including in the first and second Trump Administration as acting Legal Adviser (General Counsel) of the Department of State and Senior Advisor to Secretary of State Marco Rubio.

Mr. String is a leading authority on economic sanctions, export controls, inbound and outbound investment rules, and other regulations impacting national security and foreign policy administered by the Departments of the Treasury, Commerce, State, and Defense. He represents clients before the Committee on Foreign Investment in the United States (CFIUS) in connection with cross-border investment, security clearances, and classified government contracting. He also advises clients on investigations by Congress and the Executive Branch involving cybersecurity, defense, intelligence and foreign relations issues. He has extensive experience with international arbitration and international litigation in US courts involving the Foreign Sovereign Immunities Act (FSIA), immunities and the extraterritorial application of US law.

Prior Experience 

Previously, he served as Senior Advisor to Secretary of State Marco Rubio and as a member of the Trump-Vance presidential transition team. In the first Trump Administration, he was acting Legal Adviser (General Counsel) of the US State Department (2019-2021), leading a team of nearly 400 attorneys and staff and serving as the chief legal officer of the Department and principal legal adviser to Secretary of State Michael Pompeo. He oversaw the US government’s international litigation portfolio and represented the United States before the International Court of Justice (ICJ) and the Iran-US Claims Tribunal, arguing before the ICJ in Iran v. United States—Alleged violations of the 1955 Treaty of Amity. 

Previously, he served as acting Assistant Secretary for Political-Military Affairs (2018-2019), supervising the US Government’s $200 billion annual defense trade portfolio and administration of the International Traffic in Arms Regulations (ITAR), and as Deputy Chief Counsel and Senior Professional Staff Member on the US Senate Committee on Foreign Relations (2006-2013). 

Mr. String is an officer in the US Navy Reserve with domestic and overseas tours supporting European Command, the Joint Chiefs of Staff, and electronic warfare squadron VAQ-209.

Professional Activities

Mr. String is a Senior Fellow at the Robert Strauss Center for International Security and Law at the University of Texas was previously a scholar at the Aspen Institute Berlin. His commentary on legal and national security issues has appeared in, among other outlets, The Wall Street Journal, Foreign Affairs, Reuters and Bloomberg. He speaks fluent German.

Insights & News

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Credentials

  • Education

    • JD, Georgetown University Law Center

      magna cum laude Editor, The Georgetown Law Journal, Global Law Scholar

    • MA, University of Vienna

      Fulbright Scholar

    • BA, University of Notre Dame

      magna cum laude

      John Sheehan Prize

  • Admissions

    • District of Columbia

    • New York

  • Government Experience

    • Department of State

      Office of the Legal Adviser

      Acting Legal Adviser

    • Department of State

      Bureau of Political-Military Affairs

      Acting Assistant Secretary and Deputy Assistant Secretary

    • Department of State

      Office of the Deputy Secretary

      Senior Adviser to Deputy Secretary of State

    • Federal Legislative Branch

      US Senate

      Deputy Chief Counsel and Senior Professional Staff Member

    • Department of Defense

      US Navy Reserve

      Commissioned Officer

Credentials

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