UNITED NATIONS >> Warning that the world has a bad case of “trust deficit disorder” and risks “runaway climate change,” U.N. Secretary-General Antonio Guterres urged global leaders today to abandon unilateralism and reinvigorate cooperation as the only way to tackle the challenges and threats of increasingly chaotic times.

The U.N. chief painted a grim picture of the state of the world in his opening address to the annual gathering of presidents, prime ministers, monarchs and government officials from the U.N.’s 193 member nations. He pointed to rising polarization and populism, ebbing cooperation, “fragile” trust in international institutions and “outrage” at the inability to end wars in Syria, Yemen and elsewhere.

“Democratic principles are under siege,” Guterres said. “The world is more connected, yet societies are becoming more fragmented. Challenges are growing outward, while many people are turning inward. Multilateralism is under fire precisely when we need it most.”

In contrast, U.S. President Donald Trump defended an America-first policy, rejecting “global governance, control and domination.” He said he expects other nations to honor America’s sovereignty in return.

“America is governed by Americans,” Trump said in his speech. “We reject the ideology of globalism, and we embrace the doctrine of patriotism.”

But French President Emmanuel Macron assailed self-interest in his address soon after Trump, saying “nationalism always leads to defeat.”

He drew loud applause for his impassioned plea against isolationism and for global cooperation.

“Friends, I know you may be tired of multilateralism. I also know that the world is flooded with information, and one becomes indifferent. It all starts to look like a big show,” he said. “Please, don’t get used to it, don’t become indifferent. Do not accept the erosion of multilateralism. Don’t accept our history unraveling. I’m not getting used to this, and I’m not turning my head.”

In his speech, Iranian President Hassan Rouhani took a dig at Trump over the issue — indirectly, if not by name.

“Confronting multilateralism is not a sign of strength; rather it is a symptom of the weakness of intellect — it betrays an inability in understanding a complex and interconnected world,” Rouhani said.

Iran has been a target of escalating U.S. accusations over its nuclear and missile programs and international terrorist activities. It vehemently denies any nuclear ambitions or involvement in international terrorism.

Trump earlier had blasted what he called Iran’s “corrupt dictatorship,” saying he has launched an “economic pressure” campaign against the country. The U.S. withdrew this year from a 2015 nuclear deal between Iran and world powers. Rouhani accused the U.S. of trying to overthrow his government, rejecting bilateral talks after Trump predicted stepped-up U.S. sanctions would get Tehran to negotiate over its nuclear program.

Guterres highlighted two challenges that have taken on “surpassing urgency” since last year: climate change and new risks from advances in technology.

“Climate change is moving faster than we are,” he warned. “If we do not change course in the next two years, we risk runaway climate change. … Our future is at stake.”

Guterres said artificial intelligence, blockchain and biotechnology can potentially “turbocharge progress,” but also pose risks and serious dangers.

Technology stands to change or eliminate some jobs and is being misused for sexual abuse, for terrorism and for malicious acts in cyberspace including disinformation campaigns, discrimination against women and for reinforcing “our male-dominated culture,” he said.

“The weaponization of artificial intelligence is a growing concern,” he added.

General Assembly President Maria Fernanda Espinosa Garces opened the gathering by asking the VIPs to stand in silent tribute to former Secretary-General Kofi Annan, who died Aug. 18 at age 80.

Espinosa Garces, who was Ecuador’s foreign minister, echoed Guterres’ appeal on multilateralism, saying the General Assembly is “the only place where a meeting of this kind is possible,” and where all countries “have the opportunity to hear and be heard.”

She said the U.N.’s global contribution has been immense, from international law and the promotion of peace to human rights, combatting poverty and preserving the environment.

“The reality is that the work of the United Nations is as relevant today as it was 73 years ago,” she said. “Multilateralism stands alone as the only viable response to the global problems that we are faced with. To undermine multilateralism, or to cast a doubt upon its merits, will only lead to instability and division, to mistrust and polarization.”

Brazil’s President Michel Temer also focused on threats to global cooperation.

“We live in times clouded by isolationist forces,” he said. “Old forms of intolerance are being rekindled. Unilateral relapses are, today, increasingly less of an exception.”

“However, these challenges should not and cannot possibly intimidate us. Isolationism, intolerance, unilateralism — we must respond to each of these different trends with the very best of our peoples,” Temer said.

Turkey’s President Recep Tayyip Erdogan was sharply critical of the veto power wielded by the five permanent members of the Security Council — the U.S., Russia, China, Britain and France — and warned that the U.N. risks becoming an organization with “a reputation for failure” if it continues catering to them “while standing idle to the oppression in the other parts of the world.”

He cited genocides in Bosnia and Rwanda and the failure to end the Israeli-Palestinian conflict, calling for the Security Council to be restructured to reflect the 21st century.

This year, 133 world leaders have signed up to attend the session, which ends Oct. 1, a significant increase from the 114 leaders last year. Populist leaders attending include Poland’s President Andrzej Duda and Italy’s Premier Giuseppe Conte, along with the foreign ministers of Hungary and Austria.

China’s Foreign Minister Wang Yi warned at Monday’s U.N. “peace summit” honoring the 100th birthday of South African anti-apartheid campaigner Nelson Mandela that “unilateralism and protectionism are on the rise.”

He likely had Trump in mind, since the U.S. and China have been engaged in a trade war in recent months, with the two sides imposing higher tariffs on imports from each other.

Wang said “the U.N. is the symbol of multilateralism” and he urged the international community to “stand united under the umbrella of multilateralism, uphold the central role of the U.N. in international affairs, and provide more predictability and stability in this turbulent world.”

In speeches and nearly 350 meetings on the assembly sideline, the conflicts, hotspots and issues contributing to that turbulence will be debated.

The seven-year conflict in Syria and the three-year war in Yemen that has sparked the world’s worst humanitarian crisis and now seriously threatens large-scale famine are certain to be in the spotlight, along with African hotspots including Libya, South Sudan, Central African Republic, Mali and Congo.

The U.S., which holds the rotating presidency of the U.N. Security Council in September, has scheduled two meetings, one chaired by Trump on Wednesday that was initially to focus on Iran but has now been broadened to “nonproliferation” of nuclear, chemical and biological weapons.

The second one, to be chaired Thursday by U.S. Secretary of State Mike Pompeo, is on North Korea, the one major issue where there is a glimmer of hope for progress. The 15 council nations have been united in imposing increasingly tough sanctions to try to rein in Pyongyang’s nuclear program. But that unity appears to be at risk over enforcement of sanctions and the broader issues of how to achieve denuclearization of the Korean peninsula, and when sanctions should be lifted.