US President Donald Trump has nominated White House deputy chief of staff Kirstjen Nielsen to be the next US homeland security secretary.

Nielson previously was the Department of Homeland Security (DHS) chief of staff when John Kelly led the department for the first six months of the Trump administration. Kelly stepped down as homeland security secretary in July to become White House chief of staff and Nielson came to the White House with him. Elaine Duke has been serving as acting DHS secretary since then.

Nielson worked for former President George W. Bush on the White House Homeland Security Council and also previously headed legislative policy and government affairs at the Transportation Security Administration (TSA), which is part of DHS.

Trump said in Oct. 12 remarks at the White House that Nielson was “right by [Kelly’s] side” during his tenure as homeland security secretary. “There will be no on-the-job training for Kirstjen,” Trump said. “She is ready on day one.”

Trump noted that, under Bush, Nielson “oversaw policy and implementation related to protecting our critical infrastructure, our cybersecurity, counterterrorism and emergency preparedness.”

Nielson must be confirmed by the US Senate, which appears likely. She would take over DHS as the department oversees, among other things, the implementation of enhanced security measures for all US-bound airline flights and recovery efforts in Puerto Rico in the aftermath of Hurricane Maria.

Aaron Karp