Kirstjen Nielsen
U.S. Secretary of Homeland Security Kirstjen Nielsen speaks on migrant children being separated from parents at the southern border. Nielsen suddenly resigned her post on April 7, 2019. Alex Wong/Getty Images

Kirstjen Nielsen, the former deputy to former White House chief of staff John Kelly, unexpectedly resigned as Secretary of the Department of Homeland Security immediately after what is reported to be a tempestuous meeting with president Donald Trump Sunday.

Trump announced Nielsen’s “resignation” in a tweet the same day. Media sources said Nielsen had first submitted her hasty letter of resignation, which seemed to have been rushed because she even got the date wrong.

Her letter read, “I hereby resign from the position of Secretary of the U.S. Department of Homeland Security (DHS), effective April 7th 2018 (sic)."

"Despite our progress in reforming homeland security for a new age, I have determined that it is the right time for me to step aside."

For his part, Trump tweeted, "Secretary of Homeland Security Kirstjen Nielsen will be leaving her position, and I would like to thank her for her service.”

"I am pleased to announce that Kevin McAleenan, the current U.S. Customs and Border Protection Commissioner, will become Acting Secretary for @DHSgov. I have confidence that Kevin will do a great job!"

Shortly after posting this tweet, Trump tweeted that the "Country is FULL!"

According to CNN's sources, Nielsen did not willingly resign. Instead, she was pressured to do so and did not "fight not grovel" to keep her position, pointing to instances wherein she drew the ire of the president.

Political pundits noted Trump’s anger at Nielsen had been simmering over the past few weeks, driven by his perception she wasn’t doing enough to stanch the flow of legal and illegal immigration into the U.S.

Trump seemed to blame Nielsen over illegal immigration and the rising number of families arrested at the U.S.-Mexico border.

At a previous Cabinet meeting, Nielsen considered resigning after Trump berated her for not acting strongly enough on preventing illegal immigration, CNN noted. Trump’s ire also seems to have revived his suspicions Nielsen was still under the influence of her former boss, Kelly, who Trump fired on January 2, 2019.

By Business Insider’s count, Nielsen is the 32nd senior White House official or member of the cabinet to have either resigned or fired since Trump came into office in January 2017.

During her 16 months as DHS secretary, Nielsen became the face of Trump’s anti-immigrant policies. She drew the derision of Democrats and human rights activists for separating immigrant children from the parents and housing them in what critics termed as concentration camps for kids.

But even her heavy-handed approach wasn’t enough for Trump.

House Speaker Nancy Pelosi (D-CA) said, "It is deeply alarming that the Trump Administration official who put children in cages is reportedly resigning because she is not extreme enough for the White House's liking."

“The President's dangerous and cruel anti-immigrant policies have only worsened the humanitarian suffering at the border and inflicted vast suffering on the families who have been torn apart,” she added.

Homeland Security Kirstjen Nielsen
U.S. Secretary of Homeland Security Kirstjen Nielsen speaks on migrant children being separated from parents at the southern border. Nielsen suddenly resigned her post on April 7, 2019. Alex Wong/Getty Images

House Homeland Security Committee Chairman Bennie Thompson (D-MS) said Trump’s “dangerous and cruel anti-immigrant policies have only worsened the humanitarian suffering at the border and inflicted vast suffering on the families who have been torn apart."

"Hampered by misstep after misstep, Kirstjen Nielsen's tenure at the Department of Homeland Security was a disaster from the start. It is clearer now than ever that the Trump Administration's border security and immigration policies -- that she enacted and helped craft -- have been an abysmal failure and have helped create the humanitarian crisis at the border.”

On the other hand, Republicans praised Nielsen for her work.

"Secretary Nielsen served her country honorably as Homeland Security Secretary, despite facing numerous challenges including dire conditions at our southwest border," said Rep. Mike Rogers (R-AL), the top Republican on the House Homeland Security Committee.