President Trump canceled his face-to-face summit with North Korean leader Kim Jong Un, citing threats from the rogue regime. 

In a letter addressed to Kim, Trump said the June 12 summit in Singapore would be "inappropriate," pointing to "hostility" from Pyongyang in recent weeks. 

"Based on the tremendous anger and open hostility displayed in your most recent statement, I feel it is inappropriate, at this time, to have this long-planned meeting. Therefore, please let this letter serve to represent that the Singapore summit, for the good of both parties, but to the detriment of the world, will not take place."

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Reacting to the breaking news on "America's Newsroom," Harvard Law professor emeritus Alan Dershowitz said he would not "second-guess" Trump's decision, adding that the president "had no choice" but to walk away from the negotiations.

"We have most of the cards and I think the president is playing them well," he said.

Earlier this week after meeting with the president of South Korea, Trump expressed disappointment at a change in "attitude" from Kim after a recent trip to China. 

Dershowitz said the President of the United States cannot meet with a dictator who threatened the U.S. with nuclear weapons under the current circumstances. He predicted that the summit will happen down the road on "somewhat better terms."

Watch the segment above.

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