Donald Trump’s connections to Russia have been the subject of intense scrutiny since he became President. The United States intelligence community has already concluded that the Russian government interfered in the 2016 election and “developed a clear preference for President-elect Donald Trump.”

Now, an investigation led by Special Counsel Robert Mueller is seeking to determine if any of Trump’s inner circle colluded with the Russians to make this happen. Recently, Mueller has broadened the focus of his investigation to include Russian purchases of, and investments in, Trump properties going back at least a decade.

The findings and outcome of those inquiries remain to be seen. But for now many suspect that Trump owes much of his success in business to his close ties to Russia, and by extension his current position as the president.

Trump’s links to Russia stretch back 30 years. In 1987, he first flew to Moscow to discuss a hotel project in Moscow. This deal never materialized, but Trump would try to make the Trump Tower Moscow project happen at least five more times in the years that followed, including a final attempt during his presidential campaign.

His first attempts took place during a time of great change in Russia. After the Soviet Union collapsed in 1991, President Boris Yeltsin abruptly shifted the country to a market economy. Vast state-held assets in oil, coal, mining and banking were snapped up by opportunists, many of whom later became known as the oligarchs.

When Vladimir Putin succeeded Yeltsin as president in 2000, he used the Russian intelligence services to force through a deal between the government and Russian mobsters and oligarchs. They could continue to operate freely as long as they helped consolidate his power base and serve his financial interests.

The result is a chain of events which created a massively wealthy elite class that spend vast sums of money internationally. Seeing an opportunity, Donald Trump Jr. traveled to Russia six times in 18 months looking for investments, according to a 2008 statement he made at a real estate conference that was posted online by a trade publication and cited by the Chicago Tribune. During that speech he acknowledged that he felt the presence of corruption, saying “It is a question of who knows who, whose brother is paying off who… It really is a scary place.”

President Trump’s dealings with Russians may be catching up with him. In a revealing interview with the New York Times, the President was asked about the bounds and scope of Special Counsel Mueller’s investigation. He responded: “… I mean, it’s possible there’s a condo or something, so, you know, I sell a lot of condo units, and somebody from Russia buys a condo, who knows?”