Kristi Noem out at U.S. Department of Homeland Security

U.S. President Donald Trump on Thursday fired his embattled Homeland Security Secretary Kristi Noem, after mounting criticism over her leadership of the department, including the handling of the administration’s immigration crackdown and disaster response.

Trump, who said he would nominate in her place Oklahoma Republican Sen. Markwayne Mullin, made the announcement on social media on Thursday, two days after Noem faced a grilling on Capitol Hill from both fellow Repubican members as well as Democrats.

Trump says he’ll make Noem a “Special Envoy for The Shield of the Americas,” a new security initiative that he said would focus on the Western Hemisphere.

Noem, took the stage to address a Department of Homeland Security event moments after Trump’s announcement but made no immediate mention of her ouster. Instead, she read from prepared remarks, including reinforcing Trump’s message from the State of the Union last month.

Noem is the first cabinet secretary to be moved during Trump’s second term. Noem’s departure caps a tumultuous tenure overseeing immigration enforcement tactics that have been met with protests and lawsuits.

She ​faced criticism in January when she quickly labelled two U.S. citizens fatally shot by federal immigration agents in Minneapolis as committing “domestic terrorism.” Videos that emerged after the deaths undercut the assertion by Noem and other Trump officials that the two deceased — ​Renee Good and Alex Pretti — were violent aggressors.

WATCH | Noem stands by her accusations:

Noem stands by remarks calling U.S. citizens killed in Minneapolis terrorists

During congressional testimony on Tuesday, U.S. Homeland Security Secretary Kristi Noem declined to retract or apologize for her remarks in January calling two U.S. citizens shot dead by federal immigration officers in Minneapolis domestic terrorists. Accounts from local officials and bystander video contradicted her comments. Noem’s hearing was interrupted at times by shouting protesters.

Blistering criticism from both sides

The public backlash over the deaths led the Trump administration to move to a ⁠more targeted approach to immigration enforcement ⁠in Minnesota after months of sweeps through U.S. cities that led to violent ‌clashes with residents opposing the crackdown.

Noem faced blistering criticism from Democrats and some Republicans in congressional hearings this week over those issues and others.

The former South Dakota governor was also criticized over the way her department has spent billions of dollars allocated to it by Congress.

One particular point of scrutiny was a $220 million ad campaign featuring Noem that encouraged people in the country illegally to leave voluntarily.

Noem told lawmakers that Trump was aware of the campaign in advance, but Trump disputed that in an interview Thursday with Reuters, saying he did not sign off on the ad campaign.

Aside from immigration, Noem also faced criticism — including from Republicans — over the pace of emergency funding approved through the Federal Emergency Management Agency and for the Trump administration’s response to disasters.

Mullin would need to be confirmed by the Senate, but under a federal law governing executive branch vacancies, he would be allowed to serve as an acting homeland security secretary as long as his nomination is formally pending.