As a proponent of an "America First" approach to international relations, Trump will be closely watched by U.S. allies and adversaries during his address before the General Assembly on Tuesday, and U.N. Ambassador Nikki Haley said last week that people should expect tough talk.
"I personally think he slaps the right people, he hugs the right people, and he comes out with [the] U.S. being very strong, in the end,” she said.
Ahead of Trump's address, here's a look back at what he's said about the United Nations in the past.
He's a 'very big fan' of the U.N.
Before he launched his political career, Trump testified in 2005 before a Senate Homeland Security and Governmental Affairs subcommittee to discuss the cost of renovating the U.N. headquarters in New York.
At the time, he said he was a "big fan" of the United Nations and said he had the Trump World Tower luxury apartment building constructed across the street from the U.N. because he liked it so much.
"I'm a big fan, a very big fan of the United Nations and all it stands for," he said. "I can't speak as to what's been happening over the last number of years because it certainly hasn't been good, but the concept of the United Nations and the fact that the United Nations is in New York is very important to me and very important to the world, as far as I am concerned."
The U.N.'s marble tiles look 'cheap'
In 2012, Trump took to Twitter to criticize an architectural detail of the United Nations interior, saying the 12-inch marble tiles look "cheap" and that he would replace them with larger marble slabs.
The U.N. is 'not a friend of democracy'
During the 2016 presidential election, Trump spoke before the American Israel Public Affairs Committee, arguing that the U.N. is "not a friend of democracy." The comments came during the part of Trump's speech that discussed the deal the Obama Administration made with Iran over its nuclear program. He shunned the U.N. at the time for "utter weakness and incompetence."
"The United Nations is not a friend of democracy, it's not a friend to freedom, it's not a friend even to the United States of America where, as you know, it has its home. And it surely is not a friend to Israel ... So with the president in his final year, discussions have been swirling about an attempt to bring a Security Council resolution on terms of an eventual agreement between Israel and Palestine. Let me be clear: An agreement imposed by the United Nations would be a total and complete disaster. The United States must oppose this resolution and use the power of our veto, which I will use as president 100 percent."
The U.N. 'isn't doing anything to end the big conflicts'
After securing the Republican nomination in May of 2016, Trump discussed what a White House would look like under his administration in an interview with the New York Times. When talking about certain Cabinet positions, he had this to say about his future U.N. ambassador:
“I think about a U.N. ambassador, about a secretary of defense and secretary of treasury, but I think more about winning first,” Mr. Trump said. “Otherwise I’m wasting time. I want people in those jobs who care about winning. The U.N. isn’t doing anything to end the big conflicts in the world, so you need an ambassador who would win by really shaking up the U.N.”
The U.N. is 'just a club for people to talk and have a good time'
As president-elect, Trump promised in December of 2016 to shake up the U.N. saying " things will be different after Jan. 20th" in a Dec. 23 tweet. His criticisms took on a harsher tone after the Obama Administration abstained from a U.N. Security Council vote on a resolution that condemned Israeli settlements in the West Bank. On Dec. 26, Trump said the body "has such great potential but right now it is just a club for people to get together, talk and have a good time. So sad!"
Later that week, when asked by a reporter whether or not he wanted the U.S. to leave the U.N., Trump accused the institution of causing problems rather than solving them.
“When do you see the United Nations solving problems? They don't. They cause problems,” he said. “So, if it lives up to the potential, it's a great thing. And if it doesn't, it's a waste of time and money.”
In early January, then President-elect Trump spoke to United Nations Secretary-General Antonio Guterres and had what was described as a "very positive discussion." According to U.N. spokesman Farhan Haq, "the secretary-general said that he looked forward to engaging with the president after his inauguration.”
The U.N. 'hasn't lived up to the potential'
As president, Trump hosted a working lunch at the White House with U.N. Security Council Ambassadors on April 24. At that lunch, he had more positive things to say about the institution, though he maintained his belief that it was not meeting its full potential.
"I think that the United Nations has tremendous potential — tremendous potential — far greater than what I would say any other candidate in the last 30 years would have even thought to say. I don’t think it’s lived up — I know it hasn’t lived up to the potential. I mean, I see a day when there’s a conflict where the United Nations, you get together, and you solve the conflict. You just don’t see the United Nations, like, solving conflicts. I think that’s going to start happening now. I can see it. And the United Nations will get together and solve conflicts. It won’t be two countries, it will be the United Nations mediating or arbitrating with those countries."