"This Is All About Money Laundering"

"If you are involved in criminal activity, you are subject to blackmail. And if the criminals who can blackmail you have connections to a foreign government—say, Russia—then that government has blackmail leverage. Ten years ago, Donald Trump Jr. casually said, 'Russians make up a pretty disproportionate cross-section of a lot of our assets.' And as recently as 2014, Eric Trump told a reporter, 'We don't rely on American banks. We have all the funding we need out of Russia,' which is quite different than his current explanation that the Trump Organization does not require outside funding at all.
"The secret sauce of Trump's real-estate business in its early stages was his ability to manipulate the media and willingness to borrow massive sums and not pay them back. When he exhausted his ability to stiff his creditors, the new secret sauce became a willingness to take money from shady overseas sources, especially (but not exclusively) Russian oligarchs looking either to park their cash overseas, or to gain some measure of influence. Whether Russia was investing in Trump for the purpose of gaining some hidden leverage over him is not incidental to the Mueller investigation but its very heart."

At New York, Jonathan Chait explains why Donald Trump does not want to release his tax returns.