09/17/2017 17:02 EDT | Updated 09/17/2017 17:02 EDT

Trump Mocks 'Rocket Man' Kim Jong Un Ahead Of UN Address

The president is conferring with other world leaders.

WASHINGTON ― President Donald Trump on Sunday affirmed in a tweet that he was conferring with world leaders on North Korea's growing nuclear program, appearing to refer to North Korean leader Kim Jong Un as "Rocket Man."

Shortly after the tweet, the White House released a more measured description of Trump's phone call with South Korea's president, Moon Jae-in, and administration officials appeared on the Sunday morning talk shows to both defend and clarify the president's often bombastic and vague rhetoric.

United Nations Ambassador Nikki Haley said that "North Korea is already starting to feel the pinch" of the U.N. security council deciding unanimously last week to impose renewed sanctions on the regime.

Yet Trump derided the sanctions as "not a big deal."

"I think everybody in the international community sees what a big deal it is, but also, we know the importance of enforcement," Haley said Sunday on CNN's "State of the Union."

Trump is preparing to face a major test on Tuesday, when he is slated to address his first meeting of the United Nations General Assembly. North Korea is expected to be a top priority among the world leaders gathered in New York.

Asked to clarify Trump's stance, national security adviser H.R. McMaster reiterated that Trump would consider "all options," including military action, if the sanctions are insufficient in getting North Korea to stop its nuclear development.

North Korean leader Kim Jong Un watches the launch of a Hwasong-12 missile in this undated photo released by North Korea's Korean Central News Agency on Sept. 16, 2017.

"We all have our doubts about whether or not that's going to be enough," McMaster said of the sanctions, while appearing on ABC's "This Week." "And so we have to prepare all options."

Trump has said that the U.S. will respond with "fire and fury" as North Korea continues to ratchet up missile and weapons tests related its nuclear program.

Facing limited diplomatic options, Trump and administration officials have repeatedly threatened military action, but have offered vague suggestions of what that may entail.

Haley defended Trump's rhetoric as "not an empty threat."

"What we were doing was being responsible where North Korea is being irresponsible and reckless," she said on CNN. "We were being responsible by trying to use every diplomatic possibility that we could possibly do."

But when asked if Trump was specifically referring to military action, she said: "You have to ask the president what 'fire and fury' meant."

Also on HuffPost