Kirstjen Nielsen, the former secretary for the Department of Homeland Security who left her post in April, is rejoining the administration in a minor role.

The White House announced Tuesday evening the appointment of Nielsen as a member of the National Infrastructure Advisory Council, a Department of Homeland Security entity. The board has up to 30 members from the private sector who advise the White House on best practices for reducing physical and cyberthreats to the country’s critical infrastructure.

Nielsen’s appointment comes six months after she stepped down from her post atop the 240,000-member department. She was secretary for 16 months.

Nielsen, a lawyer, left the private sector for the Transportation Security Administration shortly after the Sept. 11, 2001, terror attacks. Her time at the TSA was her only experience in homeland security before serving in 2017 as the assistant to her predecessor, former Department of Homeland Security Secretary John Kelly.

She then went to the White House and worked as then-chief of staff Kelly’s principal deputy. Trump nominated Nielsen in October 2017 to lead the Department of Homeland Security, and she was confirmed in a 62-37 vote.

It's not clear where she has worked since April, though she had previously founded her own consulting firm that focused on protecting critical infrastructure.

Her departure came as Trump was growing frustrated due to the spike in migrant families heading to the United States-Mexico border. Nielsen left homeland security just weeks shy of the peak of what the Trump administration described as a “border crisis” involving record-high numbers of families arriving at the U.S.-Mexico border.

Trump proposed closing the entire southern border to deal with the flow. A Washington Examiner investigation revealed doing so would have interrupted $300 billion worth of annual trade that is processed by Customs and Border Protection at southern border ports of entry.

The advisory board Nielsen is joining was created by President George W. Bush in October 2001.