The author of a book on President Trump's negotiating tactics said that he expects Trump to be aggressive right away during Tuesday's historic summit with Kim Jong Un.

Brad Thomas, the author of "The Trump Factor," called the president the "dealmaker-in-chief" and said that one of his most strategic tools is his toughness.

"I fully expect him to go in with, really, guns loaded and he's going to really charge like a rhino," Thomas said Sunday on "Fox & Friends."

Thomas added that he believes the president knows what he wants Tuesday's outcome to be, and that his team will implement an effective strategy.

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"Those first minutes are going to tell a lot," he said, noting the president's remarks that he'll know right away if the meeting will yield a positive result.

"You know the way they say that you know if you're going to like somebody in the first five seconds? You ever hear that one? Well, I think that very quickly I'll know whether or not something good is going to happen," Trump said on Saturday.

Thomas said that he has full confidence in the president ahead of Tuesday's meeting, but that it would be only the first brick in the foundation of a potential resolution.

"Trump Tower wasn't built in a day, Rome wasn't built in a day and I don't think this summit's going to be done in a day," he said.

Watch the segment above.

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