President Donald Trump caught everyone off guard by suddenly firing Homeland Security Secretary Kristi Noem — but being out of a job could just be the start of her problems.That's because, according to at least some observers, the thing that appears to have prompted Trump to fire her may be a federal crime.According to the New York Post, Trump said that Noem lied to Congress when she claimed during an intense hearing she had the president's personal sign-off for a $220 million ad campaign for the Department of Homeland Security that featured her prominently, riding a horse in front of Mount Rushmore: "Two sources close to the White House told The Post that Trump is furious that Noem testified that he approved of the ads — and set in motion his later move to fire her."The trouble is, she was under oath at the time she made the claims about getting Trump's approval for the ad — which, as Democratic strategist Matt McDermott pointed out on X, means that if Trump is telling the truth, Noem committed a federal crime."The President of the United States is accusing Kristi Noem of committing perjury, a federal crime," wrote McDermott.To be in real legal jeopardy, Trump's Justice Department would have to actually prosecute Noem for the offense, which doesn't appear likely. However, many other observers noted the incredible facts of the situation."NOEM screwed up DHS response to Pretti killing, stonewalled IG investigations, has seen allegations of inappropriate relations with aide Lewandowski, bought luxury jet fleet, and spent a ton on ads starring hers truly," wrote former Politico reporter Rachel Bade. "But in the end the thing that did her in was throwing her boss under the bus."