Nielsen's Exit Comes As Trump Eyes 'Tougher' Approach On Immigration

Kirstjen Nielsen's abrupt departure as secretary of the Department of Homeland Security (DHS) comes as President Trump seeks to steer his administration towards a "tougher" approach on immigration to confront a surge in migrant families heading to the U.S.

After CBS News reported Nielsen intended to resign Sunday from the position she has held since December 2017, the president confirmed on Twitter she would be leaving her position. Mr. Trump also announced he was tapping U.S. Customs and Border Protection (CBP) commissioner Kevin McAleenan to run DHS on an acting basis. 

A protégé of former White House chief of staff John Kelly, Nielsen had reportedly fallen out of favor in recent months with the president, who has been frustrated with an unprecedented flow of Central American families reaching the U.S.-Mexico border.

Related: DHS Secretary Kirstjen Nielsen Resigning After Clashes With Trump On Immigration 

During Nielsen's tenure, apprehensions of migrant families between ports of entry along the southern border have steadily increased since the summer of 2018 and have reached record highs in recent months, according to government figures. Immigration authorities apprehended about 36,000 families along the southwestern border in February, making it the busiest February for border officials in the last 12 years.

The surge has incensed Mr. Trump and one his most trusted aides, White House senior adviser Stephen Miller, a notorious immigration hardliner. The president recently vowed to cut all U.S. foreign aid to Guatemala, Honduras and El Salvador and has repeatedly threatened to close ports of entry to and from Mexico if the country's government does not do more to prevent migrants from the Northern Triangle from reaching the southern border. 

Democrats and U.S.-financed non-governmental organizations (NGOs) working in Central America believe the aid cut will backfire, both prompting more migration and penalizing poor and working-class people for the failures of their elected leaders. Economic experts have warned a closure of the border with Mexico will cause significant harm to the U.S. economy.  

Nielsen has not been the only casualty of the administration's new strategy. On Friday, the White House announced it was withdrawing the nomination of Ronald Vitiello to lead Immigration and Customs Enforcement (ICE). Asked why he made the decision, which shocked Senate Republicans who were confident Vitiello would be confirmed, Mr. Trump said his administration was taking a "tougher" direction as it pertains to immigration. 

Democrats have long called for Nielsen's resignation, albeit for different reasons. They have denounced her implementation of the president's stringent immigration agenda, including the discontinued "zero tolerance" policy that led to the separations of more than 2,600 migrant children from their families near the border. 

The administration was forced to rescind the practice after massive public uproar, but Nielsen always maintained she did not oversee a family separation policy, but rather one of increased prosecution of migrant parents crossing the border illegally.

During Nielsen's last appearance before Congress, she was accused by California Democratic Rep. Nanette Barragán of lacking any empathy when carrying out her work. "You have no feeling, no compassion," Barragán told Nielsen during a tense exchange.

Paula Reid and Major Garrett contributed to this report.