President Trump said he'll be Russian President Vladimir Putin's "worst nightmare" if things don't go well with Russia. Mr. Trump made the comments on CNBC's "Squawk Box" in an interview that aired Friday.

Mr. Trump, still facing fallout over his widely criticized Monday meeting with Putin in Helsinki, Finland, has expressed his intent to invite Putin to Washington in fall, even as his own intelligence agency leaders warn Russia will continue attempts to meddle in the November election cycle.

Mr. Trump, after calling former President Obama a "patsy" for Russia in the CNBC interview, reiterated what he has said many times before — "Getting along with President Putin, getting along with Russia, is a positive, not a negative."

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But Mr. Trump added, "Now, with that being said, if that doesn't work out, I'll be the worst enemy he's ever had. The worst he's ever had."

Then, as CNBC anchor Joe Kernan tried to draw the interview to its conclusion, Mr. Trump said, "But I think he knows that -- I'll be his worst nightmare. But I don't think it'll be that way. I actually think we'll have a good relationship."

The president's invitation to Putin appeared to shock even his own Director of National Intelligence Dan Coats, who was informed of the invitation on stage at the Aspen Security Forum Thursday. Coats shared in his interview with NBC's Andrea Mitchell that he still doesn't know what happened in the Trump-Putin meeting.

"Say that again," Coats said at the forum Thursday, when Mitchell shared news of a possible second Putin meeting. "Did I hear you?"

When Mitchell repeated the news, announced via tweet from White House press secretary Sarah Sanders, Coats responded, "Okaaay," and, "That's going to be special."