On Wednesday, Republican presidential nominee Donald Trump asked the Russians to release emails from his Democratic opponent, Hillary Clinton, if they have hacked them. He later said he was being sarcastic, but his invitation to a foreign power to meddle in the U.S. election sparked concern among foreign policy experts. So just what are Trump’s ties to Russia?

Q. What has Trump said about his connections to Russia?

A. Trump has said he has no ties. At a news conference Wednesday, he said “I have nothing to do with Russia,” indicating he has never met Russian President Vladi­mir Putin. A day earlier, he tweeted “For the record, I have ZERO investments in Russia.”

Q: Is it true that he has no investments in Russia?

A. We don’t really know. Trump has not released the financial documents that would shed light on the issue, particularly his tax returns. Breaking a tradition dating to Richard Nixon, he says he won’t make those documents public because he is being audited by the IRS.

Q: What about investments from Russia in Trump’s businesses?

A. There is strong evidence that Trump’s businesses have received significant funding from Russian investors. Most notably, Trump’s son Donald Trump Jr. made that very claim at a real estate conference in New York in 2008, saying “Russians make up a pretty disproportionate cross-section of a lot of our assets.” Donald Trump Jr. added, “we see a lot of money pouring in from Russia.”

Trump also made millions when he agreed to bring the Miss Universe pageant to Moscow in 2013, a deal financed in part by the development company of a Russian billionaire Aras Agalarov. Agalarov is a Putin ally who is sometimes called the “Trump of Russia” because of his tendency to put his own name on his buildings. At the time, Trump mingled with the Russian business elite at a swanky after-party. “Almost all of the oligarchs were in the room,” Trump bragged on returning home.

As a sign of the importance of Russian investors, partners of one of Trump’s projects then under construction in Panama visited Moscow to sell condos at the building in 2006.

Trump also made significant money from one Russian oligarch in 2008, when he sold a mansion in Palm Beach for $95 million to Russian billionaire Dmitry Rybolovlev. Trump had bought the home at a bankruptcy auction less than four years earlier for $41.4 million.

Q: Has Trump ever built a property in Moscow?

A: No, but not for lack of trying. Trump has been promising to build a Trump Tower or hotel in Moscow for 30 years. He wrote in the “Art of the Deal” in 1987 that he visited Moscow for the first time that year to explore building a hotel in partnership with the then-Soviet government. He visited again with U.S. tobacco executives in 1996; that deal got far enough that an architect drew conceptual drawings but did not come to fruition.

Trump signed a one-year deal in 2005 with a New York real estate company called the Bayrock Group to try, again, to build a Trump Tower in Moscow. In a 2007 deposition, Bayrock executive Felix Sater (a Russian immigrant with an interesting mafia-related back story) testified that he had located Russian investors for the project, as well as a site, a shuttered pencil factory named for U.S. communists Nicola Sacco and Bartolomeo Vanzetti.

Sater testified that after trips to Russia, he would “pop my head into Mr. Trump’s office and tell him, you know, ‘Moving forward on the Moscow deal.’ And he would say, ‘All right.’ ”

That effort fizzled too. But Trump promised in a 2007 court deposition that he had not given up on Moscow. “Russia is one of the hottest places in the world for investment. . . . We will be in Moscow at some point,” he said.

Indeed, in 2013, he inked another preliminary deal to build in Moscow, this time in partnership with Agalarov, who had hosted the pageant. Agalarov told The Washington Post that the project is on hold while Trump runs for president.

Q: What about Trump’s advisers?

A: They too have financial ties in Russia. His campaign chairman, Paul Manafort, managed an investment fund for a Russian aluminum magnate with close ties to Putin. (The oligarch is suing Manafort, claiming, according to litigation in the Cayman Islands, that Manafort disappeared with $19 million.)

Manafort also unsuccessfully attempted a multimillion-dollar real estate project in New York City with funds from a Ukranian energy tycoon. And he worked as an adviser to the Putin-backed Ukranian president whose 2014 ouster sparked Russian intervention in that country, which has been opposed by U.S. officials in both parties.

Trump also considered retired Lt. Gen. Michael Flynn as his vice-presidential running mate. Flynn has argued that the United States needs stronger ties to Russia to fight Islamist terrorism. In 2015 , Flynn attended a dinner honoring the Kremlin-aligned English language media company RT, where he sat near Putin.

Another Trump foreign policy adviser, Carter Page, once ran the Moscow office of Merrill Lynch and advised the state-run conglomerate Gazprom. He has spoken publicly about the possibility that a Trump presidency could result in the lifting of Ukraine-related sanctions on Russia that would help the business interests of some of his Russian contacts.

Q: What has Trump said about how he would interact with Russia if elected president?

A: Trump has said it would be a good thing for the United States to have better relations with Russia, and he has offered words of praise for Putin. When Putin said in December that Trump was a “colorful and talented” person, Trump responded that it was an “honor.” In June, he added: “A guy calls me a genius, and I’m going to renounce? I’m not going to renounce him.”

Trump said Wednesday that the United States needed better ties with Russia to fight ISIS: “Wouldn’t it be nice if we actually got along with people, wouldn’t it be nice if we actually got along, as an example, with Russia?”

Trump has also called for revamping NATO and said he would only defend NATO countries in keeping with the organization’s compact, if other nations pay more to the United States. He told the New York Times last week, for instance, that he would come to the aid of the Baltic states if they were threatened by Russia only if they “fulfilled their obligation to us.”

He told reporters this week that he would “be looking at” whether to recognize Russia’s annexation of Crimea and lift sanctions imposed when Russia invaded the Ukrainian region in 2014.

And he declined to call for Russia to stay out of the U.S. election. “I’m not going to tell Putin what to do. Why should I tell Putin what to do?”