This year's UN gathering of world leaders put an immediate spotlight Tuesday on deep differences on tackling crises from North Korea to global warming: France's president urged world leaders to work together, while America's emphasized nations' own sovereignty.
And UN Secretary-General Antonio Guterres warned that the threat of a nuclear attack is at its highest level since the end of the Cold War and cautioned about the dangers of fiery rhetoric.
All three men made their debut appearances at the UN General Assembly, where presidents, prime ministers and monarchs are gathered for six days of discussion of matters ranging from nuclear peril to climate change to refugees. But on day one, the spotlight was on U.S. President Donald Trump and France's Emmanuel Macron.
Macron, a centrist who embraced internationalism during his campaign, vowed to press ahead with the Paris accord to combat global warming, although the U.S. has said it's withdrawing from the agreement. In his speech and a subsequent news conference, Macron said he respects Trump's decision but thinks it's a mistake and will continue trying to persuade the American to reconsider.
Macron also said France won't "close any door to dialogue" with North Korea and said it would be "a grave error" to unwind the 2015 nuclear deal with Iran, which faces strong criticism from Trump. Macron also called for investing in education and health and proposed appointing a UN representative for press freedom.
Seven decades after the end of World War II and the creation of the United Nations, international bodies are confronting doubts that they are merely venues for "a game for diplomats sitting around a table" and come up short on addressing such major threats as climate change.
But "today, more than ever before, we need multilateralism" to work on global warming, war, terrorism and other issues, Macron said.
"We can only address those challenges thought multilateralism," he said, "not through survival of the fittest."
Trump, a couple of hours earlier, portrayed "a coalition of strong and independent nations that embrace their sovereignty to promote security, prosperity, and peace," but keep their own citizens' interests foremost.
"I will always put America first," he said, echoing one of his slogans from a campaign in which he often belittled the UN. He told other leaders they "should always put your countries first."
He told leaders that the United States seeks harmony and friendship, not strife, but he warned that America "can no longer be taken advantage of."
His speech came with tough words for North Korea -- he threatened to "totally destroy" the Asian nation if the U.S. is forced to defend itself or its allies against aggression -- and for the Iran pact, which Trump called "an embarrassment" to the U.S. He hinted that his administration could soon declare Iran out of compliance with the deal, which could unravel it.
North Korea's mission said its ambassador and a senior diplomat left the chamber to boycott Trump's speech, but left a note-taker to listen.
Iran's semi-official ISNA news agency said Foreign Minister Mohammad Javad Zarif called Trump's remarks "impudent and ignorant."
Israeli Prime Minister Benjamin Netanyahu heaped praise on Trump's comments and told the General Assembly that the Iran deal should be scuttled or changed to put more pressure on Tehran.
Israel sees Iran as its most dangerous adversary because of its nuclear program, development of long-range missiles and support for militant groups. Netanyahu warned that Israel would fiercely defend itself, but he made a point of adding that everyday Iranians "are not our enemy."
Guterres, meanwhile, put "nuclear peril" as the leading global threat and added that "fiery talk can lead to fatal misunderstandings."
His message was implicitly directed at North Korean leader Kim Jong Un, but also at the U.S. and Trump. The two have traded tough rhetoric amid Pyongyang's continuing nuclear and missile tests.
Guterres said a solution to North Korea's activities must be political and stressed: "This is a time for statesmanship."
Beyond the nuclear threat, Guterres painted a grim picture of a troubled world facing grave challenges as people see rising insecurity, inequality, conflict and climate change in a world of polarized politics and fragmented societies.
"We are a world in pieces," he said. "We need to be a world at peace."
Standing in the way, he said, were nuclear peril, terrorism, unresolved conflicts and systematic violations of international humanitarian law, climate change, rising inequality, unintended consequences of innovation, and people on the move.
By long tradition, Brazil's leader is first to address the 193-member General Assembly -- a custom carried on this year by President Michel Temer, who was charged last week with obstruction of justice and leading a criminal organization.
He said that at "this time in history, marked by so much uncertainty and instability, we need more diplomacy, not less -- and "we need the UN more than before."
But Temer said it needs reform, particularly expanding the powerful Security Council to align it with the reality of the 21st century. Brazil is part of a group with Germany, India and Japan seeking permanent seats on the council.
Not far behind North Korea on the list of issues needing urgent international attention is the plight of Myanmar's Rohingya Muslims, victims of what Guterres calls a campaign of "ethnic cleansing" that has driven nearly 400,000 to flee into Bangladesh in the past three weeks. He called for the authorities in Myanmar to end military operations, allow unhindered humanitarian access and address the Rohingya's grievances.
Myanmar leader Aung San Suu Kyi, who was not at the General Assembly, defended the government earlier in the day and said her country does not fear international scrutiny. She invited diplomats to see some areas for themselves.
Guterres told leaders in his address that "I take note" of Suu Kyi's speech.
The secretary-general has repeatedly focused on the major challenge posed by climate change.
The world leaders gathered as Hurricane Maria, a Category 5 storm, pounded the small Caribbean nation of Dominica with 160 mph winds. On Monday, Guterres and top government officials from several countries devastated by the other Category 5 storm, Hurricane Irma, addressed a hastily called UN meeting and appealed for help to rebuild following that storm's destruction.
