Kupperman and his previous boss, former national security adviser John Bolton, were close to Trump and counseled the president on Ukraine matters. Kupperman was also listening in on the July 25 call between Trump and the president of Ukraine that triggered a whistleblower complaint. Cooper also represents Bolton, who refused to testify after the White House claimed he and Kupperman were among a small cadre of close advisers to the president who have absolute immunity from congressional subpoenas.