United Nations — President Donald Trump made his debut at the United Nations on Monday, using his first appearance to urge the 193-nation organization to reduce bureaucracy and costs while more clearly defining its mission around the world.But while Trump chastised the UN — an organization he sharply criticized as a candidate for president — he said the United States would "pledge to be partners in your work" in order to make the body a more effective force for peace across the globe."In recent years, the United Nations has not reached its full potential due to bureaucracy and mismanagement," said Trump, who rebuked the UN for a ballooning budget. "We are not seeing the results in line with this investment."The president pushed the UN to focus "more on people and less on bureaucracy" and to change "business as usual and not be beholden to ways of the past which were not working". He also suggested that the US was paying more than its fair share to keep the New York-based world body operational.But he also complimented steps the United Nations had taken in the early stages of reform efforts and made no threats to withdraw US support. His measured tone stood in stark contrast to his last maiden appearance at a global body when he stood at NATO's new Brussels headquarters in May and scolded member nations for not paying enough and refused to explicitly back its mutual defence pact.‘Weak and incompetent’While running for office, Trump labelled the UN as weak and incompetent, and not a friend of either the United States or Israel. But he has softened his tone since taking office, telling ambassadors from UN Security Council member countries at a White House meeting that the UN has "tremendous potential."Trump more recently has praised a pair of unanimous council votes to tighten sanctions on North Korea over its continued nuclear weapons and ballistic missile tests.Trump's big moment comes on Tuesday when he delivers his first address to a session of the UN General Assembly. The annual gathering of world leaders will open amid serious concerns about Trump's priorities, including his policy of "America First," his support for the UN and a series of global crises. It will be the first time world leaders will be in the same room and able to take the measure of Trump.The president on Monday praised UN Secretary-General Antonio Guterres, who also spoke at the reform meeting and said he shared Trump's vision for a less wasteful UN to "live up to its full potential." The US has asked member nations to sign a declaration on UN reforms, and more than 120 have done so. The president also kicked off his maiden speech at the world body by referring to the Trump-branded apartment tower across First Avenue from the UNThe speech began a busy week of diplomacy for Trump, who is slated to meet separately with more than a dozen world leaders along the sidelines of the UN His first bilateral meeting was on Monday with Israeli Prime Minister Benjamin Netanyahu during which he declared that they "are giving it an absolute go'" in Middle East peace talks.Iran major focusTrump is slated to meet with the head of the Palestinian Authority later in the week, though the White House has downplayed this week as a milestone in peace negotiations. US national security adviser H.R. McMaster said "Iran's destabilizing behaviour" would be a major focus of those discussions. While seated next to Netanyahu, a vociferous critic of the Iran nuclear deal, Trump declared "you'll see very soon" when asked if the US would stay in the agreement.Nikki Haley, the US ambassador to the UN, said Trump's criticisms were accurate at the time, but that it is now a "new day" at the UN An organization that "talked a lot but didn't have a lot of action" has given way to a "United Nations that's action-oriented," she said, noting the Security Council votes on North Korea this month.Guterres has proposed a massive package of changes, and Haley said the UN is "totally moving toward reform."Trump arrived at the UN a few months after announcing that he was withdrawing the US from an international climate agreement — negotiated during the Obama administration and signed by nearly 200 countries — but amid speculation that he might be softening his position.Gary Cohn, one of Trump's top economic advisers, reiterated during a meeting with energy ministers that Trump will proceed with the withdrawal plan unless terms more favourable to the US can be negotiated, said a senior White House official, who insisted on anonymity to discuss details of a private meeting. Major European powers that support the pact have said it cannot be renegotiated.Trump riffed on his campaign slogan when asked about his main message for the General Assembly.‘Make the United Nations great’"I think the main message is 'make the United Nations great.' Not again, 'make the United Nations great,'" Trump said as he left the UN building. "Such tremendous potential, and I think we'll be able to do this."Trump also planned talks on Monday with French President Emmanuel Macron. He also was having dinner with Latin American leaders.The United States is the largest contributor to the UN budget, reflecting its position as the world's largest economy. It pays 25% of the UN's regular operating budget and over 28% of the separate peacekeeping budget — a level of spending that Trump has complained is unfair. The U.S has yet to make its payment this year, leading some in the UN to be fearful that it may slash its contribution. An internal UN review of members' contributions is slated for next year.The Trump administration is conducting a review of the UN's 16 far-flung peacekeeping operations, which cost nearly $8 billion a year.Cutting their costs and making them more effective is a top priority for Haley but the week is also a significant one for the State Department, which has faced staff shortages while its secretary, Rex Tillerson, has been in and out of favour with Trump. A State Department spokesperson said the US delegation to the UN, while slightly down from last year, is within "historic norms."