Sullivan was a Post foreign correspondent for 14 years, working with his wife, Mary Jordan, as the newspaper's co-bureau chiefs in Tokyo, Mexico City and London.

[2] Sullivan and Jordan wrote The Prison Angel: Mother Antonia's Journey from Beverly Hills to a Life of Service in a Mexican Jail.

[3] They also co-authored with Amanda Berry and Gina DeJesus, two of the women kidnapped and held for nearly a decade by Ariel Castro in Cleveland—of Hope: A Memoir of Survival in Cleveland, published by Viking in April 2015.

Sullivan and Jordan contributed a chapter to Nine Irish Lives: The Thinkers, Fighters and Artists Who Helped Build America, edited by Mark Bailey and published by Algonquin Books in 2018.

Reporting from Saudi Arabia, Sullivan contributed to what the Pulitzer board called the Post's “commanding and courageous” coverage of the October 2018 murder of Saudi-born journalist Jamal Khashoggi.