WASHINGTON (Reuters) - U.S. President Donald Trump’s tweet about having a bigger nuclear button than Kim Jong Un’s has kept the North Korean leader “on his toes” and made clear the risks of a nuclear standoff, U.S. Ambassador to the United Nations Nikki Haley said on Sunday.

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After Kim asserted that he had a nuclear button at the ready, Trump last week dismissed the taunt by saying in a tweet that the U.S. button at his disposal was bigger and more powerful.

The comment drew criticism, including from former Vice President Joe Biden, who said it caused allies to lose confidence in Washington.

Asked on the ABC program “This Week” whether the president’s tweet was a good idea, Haley said: “I think that (Trump) always has to keep Kim on his toes. It’s very important that we don’t ever let him get so arrogant that he doesn’t realize the reality of what would happen if he started a nuclear war.”

Haley said North Korea should be clear that the United States will not reduce pressure on Kim.

“We’re not going to let them go and dramatize the fact that they have a button right on their desk and they can destroy America,” she said. “We want to always remind them we can destroy you too, so be very cautious and careful with your words and what you do.”

ClA Director Mike Pompeo also defended Trump’s nuclear button comment on the CBS “Face the Nation” program, saying it was “consistent with U.S. policy,” which was denuclearization of the Korean peninsula.

Pompeo said he still believed, as he had said in October, that North Korea is just a few months away from crossing the threshold to putting a U.S. city at risk of nuclear attack. But he declined to be more precise.

The Central Intelligence Agency head also rejected a New York Times article on Sunday that reported U.S. intelligence agencies had been unable to foresee the North’s rapid nuclear strides over the past several months.

Pompeo said U.S. intelligence had provided an understanding of North Korea’s capabilities and intent, and got the pace of the nuclear program “mostly right.”

In a separate appearance on the “Fox News Sunday” TV program, Pompeo asserted that North Korea was being “strangled” by Trump and this was the reason why it had agreed to hold official talks soon with South Korea.