Department of Homeland Security Secretary Kirstjen Nielsen is stepping down.
Rep. Joaquin Castro, chairman of the Congressional Hispanic Caucus, was critical of Nielsen, saying she spent her tenure "championing President Trump's cruel anti-immigrant agenda", and he called McAleenan's appointment "deeply disturbing". McAleenan is seen as having a good relationship with Trump and 20 years of experience, so the president felt he would be a good choice to handle the influx at the border, officials said. She repeatedly noted the limitations imposed on her department by federal laws, court settlements, and global obligations. It was created after the September 11, 2001 attacks.
US Homeland Security Secretary Kirstjen Nielsen leaves her post - President Trump
She gave no reason for her departure in her resignation letter, although she said this was the right time for her to step aside and that the U.S. is a safer place today than when she joined the administration. But despite reports he complained constantly about her performance - and that he believed she was not harsh enough - she remained steadfastly loyal. As they toured a section of newly rebuilt barriers, Nielsen was at Trump's side, introducing him to local officials.
Writing for the Daily Beast, reporter Asawin Suebsaeng revealed on Monday that two "knowledgeable sources" say that the ongoing combat between Nielsen and Miller was so intense that they "could barely be in the same room without making other top officials uncomfortable". Later, she and the president visited part of a rebuilt barrier along the border. She returned to Washington afterward as Trump continued on a fundraising trip to California and Nevada.
White House officials, Democratic lawmakers and legal experts agree that whatever Trump wants next is unlikely to be something Nielsen's successor can do swiftly - especially while working for an immigration hard-liner who is growing more and more frustrated with the increased number of attempted border crossings and apprehensions there. She walked into it prepared to resign, depending on what she heard.
Yet changing personnel can also be a sign of a decisive leader who demands results from subordinates and enforces accountability.
McAleenan has helped shape numerous Trump administration's policies on immigration. (The Trump administration has been put on notice by court injunctions ordering the reunification of some families).
Her department was responsible for implementing the proposed border wall and the separation of migrant families, and she became the face of the controversial moves.
An estimated 100,000 individuals were apprehended in March alone, the highest level in a decade according to USA border officials. More than half were families with children.