The special counsel’s investigation into President Donald Trump and his campaign team’s Russia ties has pivoted to the president’s real estate business. In particular, the probe led by Special Counsel Robert Mueller will dissect several transactions involving Trump and several of his associates’ businesses, Bloomberg reports.

This move may prove difficult as Trump’s relationship with Russian clients goes back years, somewhat blurring the boundaries of the investigation.

FBI officials are examining several Russian-backed purchases of Trump properties, including Trump’s involvement in the Manhattan SoHo development with Bayrock Capital — which was accused of committing fraud to evade taxes in 2010 — the Miss Universe pageant in Moscow four years ago and Trump’s offloading of a Florida mansion to a Russian official, Bloomberg reports.

Trump told New York Times reporters Wednesday that any examination by Mueller into his personal finances and business dealings that extend beyond Russia crosses a line.

“Look, this is about Russia. So I think if he wants to go, my finances are extremely good, my company is an unbelievably successful company. And actually, when I do my filings, people say, ‘man,’” Trump said to the Times.

The president said he does not make money off Russia. He said his transactions with the country do not extend beyond selling a condo unit every now and then to someone of Russian descent.

“I don’t have buildings in Russia. They said I own buildings in Russia. I don’t. They said I made money from Russia. I don’t. It’s not my thing. I don’t, I don’t do that,” Trump said during the interview.