The article summaries in detail how Trump has repeatedly attacked America's closet allies, particularly in the last few days, which then either directly or indirectly helps Putun.
Donald Trump refuses to criticize Vladimir Putin and rarely criticizes Russia. He also goes out of his way to help Russia, often putting Russian interests before the United States.
This can lead to one of several conclusions: (1) Trump is Russia's useful idiot, regularly helping them out of sheer admiration; (2) Trump doesn't want to criticize anything Russian because his company owes Russian oligarchs hundreds of millions dollars; and (3) Trump is a Russian-owned intelligence asset.
While (3) certainly seems plausible, given Trump's die-hard loyalty to Putin, it also beggars belief and seems like the plot of a sensational thriller. I think (2) is more plausible -- Trump is often obsequious to those who can hurt him in the wallet. His company owes hundreds of millions to a few Putin-connected oligarchs. So he will go out of his way to praise lavishly their totalitarian government to the point his fawning because painfully obvious.
Of course (1) is a possibility, too, but is Trump actually that much of a moron?
Read Chait's piece. It's a real eye-opener.