– President Trump took another leap into uncharted territory Sunday with a demand for the Justice Department to investigate whether the FBI infiltrated his 2016 campaign. Trump tweeted that he would officially demand Monday that the department "look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes - and if any such demands or requests were made by people within the Obama Administration!" In what the Washington Post describes as an effort to avoid a bigger showdown, the Justice Department bowed to the pressure late Sunday, saying its inspector general would investigate whether political motivations had tainted the investigation of alleged Russian links to Trump's campaign, which is now being led by special counsel Robert Mueller. "If anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action," said Deputy Attorney General Rod Rosenstein. Trump's tweet followed reports that an FBI informant had talked to Trump campaign advisers with alleged links to Russia, which the president called a "really big deal" in a tweet Saturday, Politico reports. Analysts described his demand for an investigation of the investigation as unprecedented. "I can't think of a prior example of a sitting president ordering the Justice Department to conduct an investigation like this one," University of Texas School of Law professor Stephen Vladeck tells the New York Times. "That's little more than a transparent effort to undermine an ongoing investigation."