President Trump calls it a "witch hunt." He's not likely to change that description once he hears the latest development into special counsel Robert Mueller's investigation into Russia's interference in the 2016 election and whether Trump's campaign had anything to do with it. On Thursday, it was announced that Mueller would be expanding the probe to look into Trump's business ties.

The businessman-turned-president has a long history of making deals with Russians, apparently enough to pique the interest of the FBI.

FBI investigators and others are looking at Russian purchases of apartments in Trump buildings, Trump’s involvement in a controversial SoHo development with Russian associates, the 2013 Miss Universe pageant in Moscow and Trump’s sale of a Florida mansion to a Russian oligarch in 2008, the person said.

Mueller's team is issuing subpoenas to banks and requesting bank records of foreign lenders, according to Bloomberg.

With the recent developments, Trump lawyer John Dowd says the probe has now strayed too far from Mueller's initial task.

"Those transactions are in my view well beyond the mandate of the Special counsel; are unrelated to the election of 2016 or any alleged collusion between the Trump campaign and Russia and most importantly, are well beyond any Statute of Limitation imposed by the United States Code," he wrote in an email.

Trump himself sounded off on Mueller's expanded probe.

''I think that's a violation," he said. "Look, this is about Russia.”

The president seemed to leave open the possibility of firing Mueller. In the same interview, he expressed regret over hiring Jeff Sessions as attorney general after the latter recused himself from the Russia investigation.