UNITED NATIONS — The head of the United Nations warned the gathered leaders of nations Tuesday that impunity, inequality and uncertainty are driving modern civilization toward “a powder keg that risks engulfing the world” — the latest in an increasing number of clarion calls from Secretary-General Antonio Guterres in recent years that the global situation is becoming intolerable and unsustainable.

“We can’t go on like this,” Guterres said in an alarming state-of-the-world address as he opened the annual high-level gathering of the U.N.’s 193 member nations.

He said the world is in “an era of epic transformation” facing challenges never seen before, with geopolitical divisions deepening, the planet heating and wars raging in the Middle East, Ukraine, Sudan and elsewhere with no clue how they will end.

“We are edging towards the unimaginable — a powder keg that risks engulfing the world,” Guterres told presidents, prime ministers and ministers in the vast General Assembly hall.

But he stopped short of saying hope was gone. “The challenges we face,” he said, “are solvable.”

The world leaders’ meeting opened under the shadow of increasing global divisions, major wars in Gaza, Ukraine and Sudan and the threat of an even larger conflict in the wider Middle East. That, Guterres said, is not helped by what he described as a creeping impunity throughout the world — on the part of leaders and many others.

Guterres called the situation in Gaza “a nonstop nightmare that threatens to take the entire region with it.” He said escalating air attacks across the Israel-Lebanon border have put Lebanon “at the brink.”

In Ukraine, he said, there is no sign of an end to the war that followed Russia’s February 2022 invasion.

In Sudan, he said, “a brutal power struggle” has unleashed “horrific violence — including widespread rape and sexual assaults” and “a humanitarian catastrophe is unfolding as famine spreads.”

The U.N. chief also pointed to “appalling levels of violence and human suffering” from Myanmar and Congo to Haiti, Yemen and beyond, and the expanding terrorist threat in Africa’s Sahel region. He said the Summit of the Future, which preceded Tuesday’s start of the nearly weeklong global gathering, was a first step. “But we have a long way to go.”

At the two-day summit, the world’s nations adopted a “Pact for the Future,” which lays out a 42-page blueprint to start addressing challenges from tackling climate change and poverty to putting guardrails on artificial intelligence and reforming the United Nations and other global institutions established after World War II to meet the needs and threats in the 21st-century world.

Guterres said meeting the challenges of a world “in a whirlwind” requires confronting the three drivers of “unsustainability” — the uncertainty of unmanaged risks, the inequality that underlies injustices and grievances, and the impunity that undermines international law and the U.N.’s founding principles.

“A growing number of governments and others feel entitled to a ‘get out of jail free’ card,” he said — a reference to the classic board game Monopoly.

Brazilian President Luiz Inácio Lula da Silva, whose country speaks first in a tradition dating to the early years of the U.N., criticized Israel’s attacks in Gaza and Lebanon, saying: “The right to self-defense became a right for vengeance, which prevents a deal for the release of hostages and delays a cease-fire.”

Lula decried the growth in global military spending for a ninth consecutive year to more than $2.4 trillion. “Those resources could have been used to fight hunger and deal with climate changes,” he said.

Turkish President Recep Tayyip Erdogan, King Abdullah II of Jordan and Iran’s new president, Masoud Pezeshkian, also spoke.

The Iranian leader accused Israel on Monday of seeking a wider war in the Middle East and laying “traps” to lead his country into a broader conflict. He pointed to the deadly explosions of pagers, walkie-talkies and other electronic devices in Lebanon last week, which he blamed on Israel, and the assassination of Hamas’ political leader Ismail Haniyeh in Tehran on July 31, hours after Pezeshkian’s inauguration.

“We don’t want to fight,” the Iranian president said. “It’s Israel that wants to drag everyone into war and destabilize the region.”

Iran supports both Hamas in Gaza and Lebanon’s Hezbollah militants.

Palestinian President Mahmoud Abbas is scheduled to speak Thursday morning and Israel’s Prime Minister Benjamin Netanyahu on Thursday afternoon.