President Donald Trump on Tuesday gave himself a superhero-like nickname as he acknowledged that the U.S. and China may not conclude a trade deal even after optimistic talks held over the weekend.

TARIFF MAN

Over Twitter, Trump called himself “Tariff Man” in a series of tweets pointing out the 90-day deadline the U.S. has announced for reaching an agreement with China before a step-up in tariff rates from 10% to 25% is set to occur.

“President Xi [Jinping] and I want this deal to happen, and it probably will. But if not remember, I am a Tariff Man. When people or countries come in to raid the great wealth of our Nation, I want them to pay for the privilege of doing so,” he said.

Read: Trump says he’s ‘Tariff Man,’ and Twitter decides it’s a superhero name

The Chinese talks are being led by Robert Lighthizer, the U.S. trade representative.

At an event in Washington, National Economic Council Director Larry Kudlow gave his reasons for optimism. “I’m just that saying in my judgment, others may disagree, we have come further and that the table of contents is larger than anything we’ve seen before,” he told a conference held by the Wall Street Journal.

Related:‘Good’ but ‘notably light’ — how analysts are reacting to the U.S.-China trade announcement

“I don’t think the 90 days thing is so important. I think it’s a matter of the directionality of it all,” Snap-on Inc. SNA, -1.87% Chairman and CEO Nicholas Pinchuk told MarketWatch. “That’s what’s encouraging. I don’t know if it can be done.”

After surging on Monday, the Dow Jones Industrial Average DJIA, -1.42% fell sharply on Tuesday, and closed lower than where the index was before Trump’s dinner with Xi.

Treasury Secretary Steven Mnuchin said U.S. markets were in a “wait and see” period to determine if there will be a “real” deal between the U.S. and China on trade. Speaking at a Wall Street Journal conference, he said “time will tell” if there is such an agreement.

The president’s schedule was light on Tuesday ahead of the funeral Wednesday of President George H.W. Bush — signing a Coast Guard funding bill as well as meeting with German auto executives including Daimler’s Dieter Zetsche and Volkswagen’s Herbert Diess.

— Robert Schroeder contributed to this report