President-elect Donald Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE has tapped a national security aide to former President George W. Bush as his counterterrorism adviser.

Tom Bossert, who served as Bush's deputy homeland security adviser, will join Trump's White House as the assistant to the president for homeland security and counterterrorism.

That role will be expanded under the Trump administration, according to a news release announcing the appointment, to give Bossert an "independent status alongside the National Security Advisor."

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Bossert will focus on protecting the country from counterterrorism threats, while retired Lt. Gen. Michael Flynn, the incoming national security adviser, will focus on "international security challenges."

"Tom brings enormous depth and breadth of knowledge and experience to protecting the homeland to our senior White House team,” Trump said in the statement.

“He has a handle on the complexity of homeland security, counterterrorism, and cybersecurity challenges. He will be an invaluable asset to our Administration.”

The elevation of Bossert gives the Trump national security staff more executive branch experience. While Flynn has no White House experience, incoming deputy national security adviser K.T. McFarland has worked in three administrations.

The two men met at Trump's Florida estate last week as Trump continues to fill out his staff. While the administration began rolling out Cabinet picks in the early portion of the transition, most of the more recent appointments have been Trump's White House staff.