Former White House press secretary Josh Earnest condemned President Trump's speech before the United Nations General Assembly on Tuesday, saying it lacked a "coherent strategy" and calling Trump's comments about North Korean leader Kim Jong Un "foolish."

"What you know that world leaders are looking for in that room is a coherent strategy for taking on the biggest challenges around the globe, and whether that is climate change, or refugee problems or rogue nations with nuclear weapons, the world looks to the United States to organize a coherent strategy," Earnest told MSNBC on Tuesday. "There is a distinct lack of coherence in the strategy that President Trump outlined today."

Earnest, who served as White House press secretary for former President Barack Obama, said the president was contradicting himself by first urging North Korea to work toward a denuclearized Korean Peninsula alongside the United Nations, but then "trashing" and promising to end the Iran nuclear deal.

Trump's lack of a clear strategy, Earnest said, hampered the ability of the United States to promote its leadership and interests on the world stage.

"It puts the United States at a disadvantage, that part of our leadership in the world and part of the way we advance our interests is being able to articulate a strategy that the world then joins us in implementing," he said. "And the coherence of the strategy was lacking in today's speech."

During his highly-anticipated speech before at the 72nd session of the U.N. General Assembly, Trump denounced Iran and North Korea, and warned "Rocket Man is on a suicide mission for himself and his regime."

Trump has adopted the name "Rocket Man" for Kim Jong Un.

When asked about the president's remarks about the leader of the rogue regime, Earnest said it is "beneath the United States" for Trump to "try to out-Kim Jong Un Kim Jong Un."

"I think it is a foolish to try to goad or provoke or mock somebody who even in President Trump's own words is on a ‘suicide mission,'" Earnest said. "How is the United States' negotiating position, or how is our national security strengthened by mocking the leader of North Korea? It is in nobody's interest, particularly the most powerful, influential, strongest, greatest country in the world, for the leader of that country to try to out-Kim Jong Un Kim Jong Un."