"Under our potential deal with China, they will purchase from our Great American Farmers practically as much as our Farmers can produce," he tweeted on Monday morning.
To those on Wall Street and other executives who make a living negotiating, the deal struck by the president who wrote "The Art of the Deal" doesn't look too artful. Not only that, the deal — to the extent there is one — raises all sorts of questions about Mr. Trump's ability to extract concessions in future negotiations.
Senator Marco Rubio, Republican of Florida, took perhaps an even dimmer view: "China is winning the negotiations," he wrote on Twitter. "Their concessions are things they planned to do anyways."
Mr. Trump's negotiating playbook is by now pretty obvious: Start with a headline-grabbing demand, beat chest loudly, then accept whatever is actually practical and call it a win.
In negotiating parlance, such a strategy involves trying to "anchor" yourself to an extreme position, knowing that the real goal line is something much less than what you've said. But Mr. Trump seems to routinely unmoor himself, leaving him exposed to the whims of those on the other side of the negotiating table.
Bruce Wasserstein, the revered investment banker who once ran Lazard and negotiated some of the biggest deals of the 1980s and '90s, wrote a passage about the art of negotiation in his book "Big Deal" that seems prophetic today.
"The tendency of inexperienced negotiators, often due to their insecurity, is to be too belligerent and inflexible," Mr. Wasserstein, who died in 2009, wrote. "A little psychology is required on the part of the negotiator. It is therefore important to be reasonable, although not obsequious, and, ideally, to give the other side enough so that its advocates feel that they have made a positive contribution and do not feel resentful."
Mr. Trump seems to bend all of the conventional rules of negotiation. He can be both belligerent and obsequious. He was both in his talks with China.
His early talk on tariffs was so combative that Senator Ben Sasse, Republican of Nebraska, said at the time, "If he's even half-serious, this is nuts." Then the president suddenly became a China jobs booster, instructing his government to find a way to ease up on ZTE, a Chinese telecommunications company that the Commerce Department said had violated sanctions by selling equipment to Iran and North Korea.
"President Xi of China, and I, are working together to give massive Chinese phone company, ZTE, a way to get back into business, fast," Mr. Trump wrote on Twitter. "Too many jobs in China lost."
His tweet looked like a clear attempt to ingratiate himself with China before the trade talks, but it also broke Mr. Trump's own negotiating rule from "The Art of the Deal": "The worst thing you can possibly do in a deal is seem desperate to make it. That makes the other guy smell blood, and then you're dead."
Part of the problem for Mr. Trump is that it is difficult to negotiate when there is disagreement within your own team about the approach to take. White House officials would have you believe that they are singing from the same hymn sheet, but they are not. Mr. Mnuchin and Larry Kudlow, Mr. Trump's top economic adviser, are often at loggerheads with their more hawkish colleagues Robert E. Lighthizer, the United States trade representative, and Peter Navarro, the president's chief trade adviser. If that isn't obvious, just look at the steady stream of anonymous quotes with each side sniping at the other over the past couple of weeks.
Maybe that's the way Mr. Trump likes it. As I reread "The Art of the Deal," I was struck by this line: "I never get too attached to one deal or one approach," he wrote. "I keep a lot of balls in the air, because most deals fall out, no matter how promising they seem at first."
That may be a practical strategy in business, but it gets more complicated when it comes to trade. Or even more high-stakes matters, like North Korea.
The page of Mr. Trump's book that stopped me in my tracks was one that might be the one by which he will ultimately be judged: "You can't con people, at least not for long. You can create excitement, you can do wonderful promotion and get all kinds of press, and you can throw in a little hyperbole. But if you don't deliver the goods, people will eventually catch on."