Historian Jon Meacham was alarmed by President Donald Trump's allegiance to Russian president Vladimir Putin -- but he's even more worried by what comes next.
The two leaders met privately for more than two hours Monday in Helsinki, Finland, and Trump came out of that meeting defeated and sided with Putin over U.S. intelligence and law enforcement agencies.
"My chief fear is that this is the middle of the journey, not the beginning and not the end," Meacham told MSNBC's "Morning Joe." "Because Vladimir Putin has a huge check in his pocket ready to cash from Donald Trump, and I don't think it's simply going to be cashed for a congenial press conference."
Meacham said there's no doubt that Trump is beholden to Putin, and he wonders what Russia will do next with that leverage over the American chief executive.
"I think there must be some other shoe to drop, to use that image," Meacham said. "There must be some other country to invade, there must be some other attempt here by Russians to expand their influence at the expense of the western, the expense of the western alliance and we have seen over the last -- not just the last 24 hours but the last six, seven days -- that the president of the United States does not have the interests, historic interests, of the western alliance and of the United States front and center."