President-elect Donald Trump speaks to reporters at his Mar-a-Lago resort in Palm Beach, Fla. (Jim Watson/Getty Images)

President-elect Donald Trump announced Tuesday that he has appointed Thomas P. Bossert, a veteran of the George W. Bush administration, as assistant to the president for homeland security and counterterrorism.

The position is a critical White House post within the National Security Council. The aide has often been the first person to brief the president when a terrorist attack takes place within the United States and has served as a critical liaison between the administration and foreign governments in the fight against terrorism.

Trump's transition office said the position would be elevated to be equal in status to that of retired Lt. Gen. Michael T. Flynn, whom Trump previously named as his national security adviser. The transition team said Bossert would focus on domestic and transnational security issues while Flynn focuses on international security challenges. Current White House officials said President Obama employs a similar structure.

Bossert served in the White House as the deputy homeland security adviser to President Bush. In that capacity, he supported and advised the president on matters of homeland and national security, counterterrorism, cybersecurity, and continuity of operations, Trump’s transition office said in announcing the pick.

“Tom brings enormous depth and breadth of knowledge and experience to protecting the homeland to our senior White House team,” Trump said in a statement. “He has a handle on the complexity of homeland security, counterterrorism, and cybersecurity challenges. He will be an invaluable asset to our Administration.”

In a statement, Bossert said he is looking forward to working with Flynn as well as “maintaining a strong, deeply respectful relationship” with state and local officials and emergency responders involved in homeland security. Bossert also noted the emerging challenges posed by cybersecurity — which came to the fore during the presidential election with hacks of Democratic email accounts.

Doug Wilson, a former assistant secretary of defense for public affairs in the Obama administration, said Bossert's challenges will include “fostering much more effective cooperation between government and the private sector.”

“The latter is key,” Wilson said. “Cyberthreats don’t respect silos; they cut across them. Bossert has been given elevated status in a Trump White House. If he uses this to butt heads and break china to achieve the kind of public-private sector cooperation on cybersecurity that has eluded us so far, he’ll be doing everyone a service.”

Since leaving the Bush administration, Bossert has run a homeland and national security consulting business and served as a senior cybersecurity fellow at the U.S. Atlantic Council. He has held other positions in federal government with the Federal Emergency Management Agency, the Small Business Administration, the Office of the Independent Counsel and the U.S. House of Representatives.

In an op-ed in the Washington Times last year, Bossert criticized President Obama for what he characterized as a resistance to “articulating a doctrine” of when to use military force, particularly against states harboring terrorists.

“He has not adequately explained his use of the military in Syria nor followed the last part of Mr. Bush’s doctrine of holding terrorists and the nations that harbor them accountable,” Bossert wrote.

“He is seeking now to avoid in Syria the use of ground forces for full-scale occupation and stabilization,” Bossert said of Obama. “History will decide if unending civil war and global mass migration are less costly and disruptive. It will also decide if airstrikes alone constitute a reasonable foreign policy when the use of force is just and necessary.”