This explains a lot.
Financial records filed last year in the secretive tax haven of Cyprus, where Paul J. Manafort kept bank accounts during his years working in Ukraine and investing with a Russian oligarch, indicate that he had been in debt to pro-Russia interests by as much as $17 million before he joined Donald J. Trump’s presidential campaign in March 2016.
The money appears to have been owed by shell companies connected to Mr. Manafort’s business activities in Ukraine when he worked as a consultant to the pro-Russia Party of Regions. The Cyprus documents obtained by The New York Times include audited financial statements for the companies, which were part of a complex web of more than a dozen entities that transferred millions of dollars among them in the form of loans, payments and fees.
I wouldn’t be surprised at all if this is the same reason Trump is adamant about not releasing his tax returns; he’s probably on the hook to the same gang for a lot more, and they’ve got him.