New York | President Joe Biden is set to deliver his final address to the UN General Assembly on Tuesday as Israel and Hezbollah militants in Lebanon are edging toward all-out war and Israel's bloodyoperation against Hamas in Gaza nears the one-year mark.

Biden is expected to use his wide-ranging address to speak to the need to end the Middle East conflict and the 17-month-old civil war in Sudan and to highlight US and Western allies' support for Kyiv since Russia invaded Ukraine in February 2022.

His appearance before the international body also offers Biden one of his last high-profile opportunities as president to make the case to keep up robust support for Ukraine, which could be in doubt if former President Donald Trump, who has scoffed at the cost of the war, defeats Vice President Kamala Harris in November.

Biden came to office promising to rejuvenate US relations around the world and to extract the US from "forever wars" in Afghanistan and Iraq that consumed American foreign policy over the last 20 years.

He achieved both goals. But his foreign policy legacy may ultimately be shaped by his administration's response to two of the biggest conflicts in Europe and the Middle East since World War II.

The Pentagon announced Monday that it was sending a small number of additional US troops to the Middle East to supplement the roughly 40,000 already in the region, because of the rising tensions. All the while, the White House insists Israel and Hezbollah still have time to step back and de-escalate.

“It's in everyone's interest to resolve it quickly and diplomatically," White House press secretary Karine Jean-Pierre told reporters as Biden made his way to New York on Monday ahead of his address at the UN.

Biden administration officials will be speaking to their counterparts on the sidelines of the UN about ideas that they believe could prevent the fighting between Israel and Lebanon from escalating, according to two senior administration officials.

The officials, who spoke on condition of anonymity to discuss private conversations, declined to offer any further details on the potential off-ramps. One of the officials said that other countries were also keen to present ideas to reduce tensions.

Biden had a hopeful outlook for the Middle East when he addressed the UN just a year ago. In that speech, Biden spoke of a “sustainable, integrated Middle East” coming into view.

At the time, economic relations between Israel and some of its Arab neighbours were improving with implementation of the Abraham Accords that Israel signed with Bahrain, Morocco and the United Arab Emirates during the Trump administration.

Biden's team helped resolve a long-running Israel-Lebanon maritime dispute that had held back gas exploration in the region. And Israel-Saudi normalization talks were progressing, a game-changing alignment for the region if a deal could be landed.

“I suffer from an oxymoron: Irish optimism,” Biden told Israeli Prime Minister Benjamin Netanyahu when they met on the sidelines of last year's UN gathering. He added, "If you and I, 10 years ago, were talking about normalisation with Saudi Arabia ... I think we'd look at each other like, Who's been drinking what?'” Eighteen days later, Biden's Middle East hopes came crashing down. Hamas militants stormed into Israel killing 1,200, taking some 250 hostage, and spurring a bloody war that has killed more than 41,000 Palestinians in Gaza and led the region into a complicated downward spiral.

Now, the conflict is threatening to metastasize into a multi-front war and leave a lasting scar on Biden's presidential legacy.

Israeli strikes on Lebanon on Monday killed more than 490 people, including more than 90 women and children, Lebanese authorities said, in the deadliest barrage since the 2006 Israel-Hezbollah war.

Israel has urged residents of southern Lebanon to evacuate from homes and other buildings where it claimed Hezbollah has stored weapons, saying the military would conduct “extensive strikes” against the militant group.

Hezbollah, meanwhile, has launched dozens of rockets, missiles and drones into northern Israel in retaliation for strikes last week that killed a top commander and dozens of fighters. Dozens were also killed last week and hundreds more wounded after hundreds of pagers and walkie-talkies used by Hezbollah militants exploded, a sophisticated attack that was widely believed to have been carried out by Israel.

Israel's leadership launched its counterattacks at a time of growing impatience with the Iranian-backed Hezbollah's persistent launching of missiles and drones across the Israel-Lebanon border after Hamas started the war with its brazen attack on October 7.

The stepped-up Israeli operations were launched shortly after a White House senior adviser, Amos Hochstein, visited Israel last week and urged the Israelis to avoid an escalation that could risk spurring a regional conflict.

“Reality is intervening,” said Bradley Bowman, a defense strategy and policy analyst at the Foundation for the Defense of Democracies in Washington. “There are contrasting interests that transcend the politics and the politicians of the US-Israel relationship.

For Israel, October 7 did happen, and the reality is they are facing a multifront threat and the current status quo is unacceptable. Sometimes to get to a better status quo, you have to escalate”.

Biden has seemed more subdued in recent days about the prospects of Israel and Hamas agreeing to a temporary cease-fire and hostage deal. But he insists that he hasn't given up.

“If I ever say it's not realistic then I might as well leave," Biden said last week when asked if the chances for a deal were quickly fading under his watch. “A lot of things don't look realistic until we get them done." Biden, in his address, also is expected to address ongoing Western support for Ukraine in its war with Russia. Biden helped galvanise an international coalition to back Ukraine with weapons and economic aid in response to Russian President Vladimir Putin's February 2022 assault on Ukraine.

Biden has managed to keep up American support in the face of rising scepticism from some Republican lawmakers — and Trump — about the cost of the conflict.

At the same time, Ukrainian President Volodymyr Zelenskyy is pressing Biden to loosen restrictions on the use of Western-supplied long-range missiles so that Ukrainian forces can hit deeper in Russia.

So far Zelenskyy has not persuaded the Pentagon or White House to loosen those restrictions. The Defence Department has emphasized that Ukraine can already hit Moscow with Ukrainian-produced drones, and there is hesitation on the strategic implications of a US-made missile potentially striking the Russian capital.

Putin has warned that Russia would be “at war” with the United States and its NATO allies if they allow Ukraine to use the long-range weapons.

Over the course of the war, Biden has previously resisted Ukrainian requests for certain weaponry, including MI Abrams tanks and F-16 fighter jets, before agreeing to allow their use because of worries about escalating tensions with Russia.

Max Bergmann, a Russia analyst at the Centre for Strategic and International Studies, said the administration has slowly come around to giving Ukraine weapons that it initially deemed “unimaginably escalatory” at the start of the war.

“Allowing Ukraine to strike further into Russian territory with US weapons would be another big step and the Biden administration is right to be deliberate,” Bergmann said.

Biden and Harris are scheduled to hold separate meetings with Zelenskyy in Washington on Thursday. The Ukrainian leader also is expected to meet with Trump this week.