[5] In 1984, Kozak was the legal advisor in the State Department's delegation that met at a midtown Manhattan hotel (while registered under pseudonyms to avoid attention) with Cuba's Vice Foreign Minister Ricardo Alarcón.

[7] While working as principal deputy legal advisor, Kozak originated an idea to settle a dispute between the U.S. government and the Chilean government over the killing of a former Chilean diplomat in exile in the United States, Orlando Letelier, and his American assistant Ronni Moffit in a 1976 car bombing near Dupont Circle in Washington, D.C.[12] As Chile was unwilling to submit to a determination by a U.S. tribunal, Kozak proposed invoking the arbitration clause of the 1914 Chile-United States peace treaty, and Chile agreed.

[12][13] In October 1985, Kozak testified before the House Committee on Foreign Affairs about recourse available to the United States government and U.S. citizens for the Achille Lauro terrorist attack.

[6][10] In early 1988, Kozak had been sent to Panama repeatedly to try to negotiate on behalf of the U.S. government directly with Panamanian President Manuel Noriega, attempting to settle on terms under which Noreiga would step down.

[16] In March 1989, as acting Assistant Secretary of State for Inter-American Affairs, Kozak advocated before Congress for funding for diplomatic efforts in Latin America.

[15] The next year, Kozak was instrumental in promoting ICITAP as the appropriate organization to train the Panamanian Defense Forces for civil law enforcement work after the overthrow of Manuel Noriega, with mixed results.

[19][8] Their staffs had disapproved of the way in which the State Department had notified the committee of a particular programs, and held Sullivan and Kozak responsible as deputy assistant secretaries at the time.

[20] In March 1993, Kozak was a deputy to U.S. Special Advisor Lawrence Pezzullo on issues related to Haiti and the deposition of Haitian president Jean-Bertrand Aristide.

[8] In September 1994, Kozak accompanied General Colin Powell on a flight to Port-au-Prince, Haiti, less than 36 hours before the planned landing of American troops there, to convince the leader of the ruling military junta that had taken control, Raoul Cedras, to leave power.

[24][25] In November 2002, Kozak spoke before a conference in Washington, D.C., sponsored by the American Enterprise Institute and charged that Belarus President Lukashenko was illegally selling arms to the regime of Saddam Hussein.

[26] Between 2005 and 2009, Kozak was a senior director on the National Security Council staff, with responsibility for democracy, human rights, international organizations, migration and detainee issues.

[5] Between 2009 and 2017, Kozak was senior adviser to the Assistant Secretary for Democracy, Human Rights and Labor, where he worked to negotiate a UN resolution on "Defamation of Religions" that respected freedom of expression.