President Trump will embark on a whirlwind series of meetings this week at the United Nations General Assembly to make two big asks of the world: Stand with us against North Korea, and hold the line against Iran’s nuclear program.

Over the course of four days beginning Monday, Trump will engage in a speed round of diplomacy that may test his patience for the notoriously factionalized, lethargic institution as well as his preference for one-on-one dealmaking in which the U.S. always holds the strongest hand.

“Next week is not going to be short on topics,” the U.S. ambassador to the United Nations, Nikki Haley, told reporters at the White House on Friday.

Haley acknowledged that foreign leaders are curious about how the unpredictable U.S. president will maneuver.

“They are all very anxious to hear what he has to say,” Haley said. “And I think that he will make quite an impact.”

Trump’s appearance at the U.N. – highlighted by an address Tuesday before the world body – is his biggest moment on the world stage since taking office. There is far more at stake than at the two economic summits in Europe he attended earlier this year.

As he welcomes leaders from nearly 200 nations to his hometown of New York, he’ll press them to join U.S. efforts to constrain missile and nuclear programs in both North Korea and Iran.

Tensions have risen sharply with both nations since Trump took office and assumed a more confrontational posture than his predecessor, Barack Obama.

“The world is still trying to take the measure of this president,” said Jon Alterman, senior vice president of the Center for Strategic and International Studies.

“For a number of leaders, this is going to be their first chance to see him, to judge him, to try to get on his good side.”