NEW YORK, NY - NOVEMBER 17: Retired Lt. Gen. Michael Flynn gestures as he arrives at Trump Tower, November 17, 2016 in New York City. President-elect Donald Trump and his transition team are in the process of filling cabinet and high level positions for the new administration. (Photo by Drew Angerer/Getty Images)
National Security Adviser H.R. McMaster is a decorated military general with a PhD and a reputation for speaking his mind.
WASHINGTON, DC - JUNE 23: FBI Director James Comey participates in a news conference on child sex trafficking, at FBI headquarters, June 23, 2014 in Washington, DC. Director Comey said that 168 juveniles have been recovered in a nationwide operation targeting commercial child sex trafficking. (Photo by Mark Wilson/Getty Images)
James Comey was nominated by President Obama as FBI Director in 2013 for a 10-year term. He was fired by President Trump in 2017.
WASHINGTON, DC - MARCH 07: Deputy U.S. Attorney General nominee Rod Rosenstein is sworn in prior to testimony before the Senate Judiciary Committee March 7, 2017 in Washington, DC. During the hearing, Democratic senators pressed Rosenstein to appoint a special prosecutor in an ongoing federal inquiry into Russian influence in the U.S. presidential election. (Photo by Win McNamee/Getty Images)
Everything you need to know about Rod Rosenstein, President Trump's deputy attorney general.
WASHINGTON, DC - MAY 11: Acting FBI Director Andrew McCabe testifies before the Senate Intelligence Committee with the other heads of the U.S. intelligence agencies in the Hart Senate Office Building on Capitol Hill May 11, 2017 in Washington, DC. The intelligence officials were questioned by the committee during the annual hearing about world wide threats to United States' security. (Photo by Alex Wong/Getty Images)
Andrew McCabe joined the FBI in 1996. He has worked on issues related to counterterrorism and national security.
NEW YORK, NY - AUGUST 08: Robert S. Mueller III, Director of the Federal Bureau of Investigation (FBI), speaks at the International Conference on Cyber Security (ICCS) on August 8, 2013 in New York City.
Oil consultant Carter Page was called an informal adviser to Trump's campaign, and then later, "never part of our campaign." The FBI obtained a FISA warrant to monitor him in 2016.
Don McGahn, general counsel for the Trump transition team, gets into an elevator in the lobby at Trump Tower, November 15, in New York City. President-elect Donald Trump is in the process of choosing his presidential cabinet as he transitions from a candidate to the president-elect.
Prior to assuming his current role at the NSA in 2014, Rogers served as the director for Intelligence for both the Joint Chiefs of Staff and US Pacific Command, and most recently as commander for the US Fleet Cyber Command.