President Donald Trump forcefully defended the United States and condemned North Korea and Iran in his first speech before the United Nations General Assembly, while trying to strike a cordial tone on the international alliances he had previously criticized.

“As president of the United States, I will always put America first,” he said. “The United States will always be a great friend to the world and especially to its allies, but we can no longer be taken advantage of or enter into a one-sided deal in which the United States gets nothing in return.”

Trump’s speech Tuesday was an important test on the world stage, as the U.N. grapples with international crises, including North Korea’s growing nuclear program, terrorism and climate change.

“Rocket Man is on a suicide mission for himself and for his regime,” Trump said, referring to his nickname for North Korean leader Kim Jong Un.

He then said the U.S. “will have no choice but to totally destroy North Korea” if the regime does not tamp down its nuclear development and if it threatens the U.S. and its allies.

In a clear nod to his conservative base, Trump pledged to “crush the loser terrorists” and “stop radical Islamic terrorism.”

He also strongly indicated that he would not remain in the Iranian nuclear deal, which is up for renewal next month, calling it “one of the worst and most one-sided transactions the U.S. has ever entered into” and “an embarrassment.”

Trump’s speech presented another opportunity to push his “America First” foreign policy vision, this time in front of an international body he has often maligned.

During his presidential campaign, Trump regularly criticized the United Nations for mismanagement and ineffectiveness. And in December, he referred to it as “a club for people to get together, talk and have a good time.”

On Monday, he pledged to “make the United Nations great,” a nod to his campaign slogan.

“The main message is ‘make the United Nations great.’ Not ‘again.’ Make the United Nations great,” Trump told reporters. “Such tremendous potential, and I think we’ll be able to do this.”

In his speech Tuesday, Trump celebrated the international alliances formed after World War II, a sharp contrast from his campaign rhetoric.

Yet he remained critical of the United Nations’ role and fiercely put forth his “America First” platform, boasting at the beginning of his scripted remarks that “the United States has done very well since Election Day.”

While in New York, Trump has been speaking with world leaders gathered for the U.N. meeting. On Monday, he met with Israeli Prime Minister Benjamin Netanyahu to discuss peace in the Middle East, which Trump has boasted he can reach, as well as the Iran nuclear agreement, which Netanyahu fiercely opposes.

“You’ll see very soon,” Trump told reporters, when asked if the U.S. would stay in the agreement.

Later in the day, Trump met with French President Emmanuel Macron, with climate change as one topic of contention. Macron has been trying to convince Trump to reverse the decision he made earlier this year to withdraw the United States from the Paris climate agreement.

According to the White House, the two leaders “discussed how best to protect the environment while promoting economic growth.”