That fateful meeting that Donald Trump Jr., Jared Kushner and Paul Manafort took with a bunch of Russians was obviously deeply problematic on its own terms, and perhaps a violation of campaign finance laws. But it also may wind up serving as a doorway that opens up to a whole array of questionable connections and actions related to Russia, on the part of President Trump, his family and his advisers.

The latest revelation — the identity of the eighth attendee at the meeting — was somehow both shocking and not surprising at all. In fact, it lets us peek into one of the main ways that Trump has been intertwined with Russian interests and actors for decades. While the possibility of campaign collusion is what started this scandal, the financial connections between Trump and Russia may wind up being just as important.

In case you missed it, that eighth attendee was one Ike Kaveladze, an associate of Emin and Aras Agalarov (the Russian pop singer and his oligarch father who were friendly with the Trumps). Some years ago, Kaveladze was the subject (but never charged) of an inquiry into an enormous money-laundering scheme that involved setting up hundreds of bank accounts and thousands of shell corporations in Delaware on behalf of shady Russians. As Sen. Mark Warner (D-Va.) put it: “I doubt if this individual who had a history of setting up thousands of fake accounts in Delaware was really there to talk about Russian adoptions.” Good guess.

So you had a lawyer with Kremlin connections, a former Russian intelligence official (though as they say, there’s no such thing as a “former” Russian intelligence official) and a man once suspected of being involved in money-laundering, all coming to peddle dirt on Hillary Clinton, a possibility so enticing that it led the candidate’s son, his son-in-law and closest adviser, and his campaign chairman to all come to a meeting with them. The latest version the Trump camp tells about the meeting is that the promised Clinton dirt was not forthcoming, and so the meeting didn’t last long. But given that they started out by lying about it — saying it just concerned Russian adoptions and hiding who was in attendance — there’s ample reason to be skeptical about whether we’ve yet gotten the whole truth.

The Post’s Ruth Marcus explains why in Donald Trump Jr. is in legal jeopardy. Hint: stupidity is not a legal defense. (Adriana Usero, Kate Woodsome/The Washington Post)

What we do know, however, is that it makes perfect sense that the Russians would have had an in with the Trump family to begin with, because Trump’s financial connections to Russia are old and deep. As Craig Unger reported in a story last week that didn’t get the attention it should have:

A review of the public record reveals a clear and disturbing pattern: Trump owes much of his business success, and by extension his presidency, to a flow of highly suspicious money from Russia. Over the past three decades, at least 13 people with known or alleged links to Russian mobsters or oligarchs have owned, lived in, and even run criminal activities out of Trump Tower and other Trump properties. Many used his apartments and casinos to launder untold millions in dirty money. Some ran a worldwide high-stakes gambling ring out of Trump Tower — in a unit directly below one owned by Trump. Others provided Trump with lucrative branding deals that required no investment on his part. Taken together, the flow of money from Russia provided Trump with a crucial infusion of financing that helped rescue his empire from ruin, burnish his image, and launch his career in television and politics. “They saved his bacon,” says Kenneth McCallion, a former assistant U.S. attorney in the Reagan administration who investigated ties between organized crime and Trump’s developments in the 1980s.

Some people saw a contradiction in Donald Trump Jr.’s 2008 statement that “Russians make up a pretty disproportionate cross-section of a lot of our assets” on the one hand, and on the other hand the Trumps’ repeated insistence that they have no investments in Russia. The latter may be true (though we don’t know for sure). But what is most certainly also true is that Russians have lots of investments in Trump. In fact, the amount of money that Russian oligarchs and alleged mobsters have put into Trump’s pockets over the years goes into the hundreds of millions of dollars. In some cases they invested in Trump projects. In many cases they bought condos in Trump’s buildings, as Unger documents. There’s the reporter who says Eric Trump told him that that they didn’t need loans from American banks for golf course projects, because “We have all the funding we need out of Russia.” Then there’s the story of the Palm Beach estate Trump bought for $41 million, then sold four years later to Russian fertilizer magnate Dmitry Rybolovlev for $95 million.

It’s entirely possible that none of Trump’s interactions with Russians over the years stepped over any legal or ethical lines. Maybe he never asked why so many Russians were showering him with money. But we have only scratched the surface of his financial entanglements with Russia. And those entanglements may end up helping explain both why Trump is so solicitous of Vladimir Putin and possibly more. Right now it seems clear his deep Russian connections and those of so many of his associates may have provided the Russians easy access to his inner circle. Believe me, if a Kremlin-connected attorney, a former Russian intelligence officer and a man once thought to be involved in money-laundering called up the Clinton campaign and said, “Hey, can we give you some info?” they wouldn’t have been quickly brought in to meet with Chelsea Clinton, Huma Abedin, and John Podesta.

But with Trump it was easy — Trump Jr. is friendly with the oligarch’s son, Manafort got $17 million from a pro-Russian party in Ukraine, and one Trump adviser after another is connected in some way to Russia, usually through their bank accounts. When some Russians want a meeting with the Trump team, they get it.

There’s one more thing we know: Robert S. Mueller III’s investigation has the resources it needs and won’t be deterred by the spin from the White House and Fox News that this is all much ado about nothing. Among other things, Mueller will probably pry from Trump what he worked so hard to conceal: Not just his tax returns as specific documents, but also the secrets and revelations contained therein, wherever they might lead. In the end, it may all turn out to be squeaky-clean. But I wouldn’t bet on it.