US President Joe Biden is set to deliver his final address to the UN General Assembly as Israel and Hezbollah militants in Lebanon are edging toward all-out war and Israel’s bloody operation against Hamas in Gaza nears the one-year mark.

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

His appearance before the international body also offers Mr 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.

US President Joe Biden speaks as he accepts the Global Citizen Award during the Clinton Global Initiative in New York (Andres Kudacki/AP)

Mr 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 the Second World War.

The Pentagon announced on 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.

“We do not believe a wider conflict in the north is in their interest or in Lebanon’s interest, ” Jon Finer, White House principal deputy national security adviser, told NPR on Tuesday.

Mr Finer added that Mr Biden administration officials would be engaging allies on the side-lines of this week’s UN high-level meetings in conversations about finding an endgame to the growing crisis.

Mr 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.

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

“I suffer from an oxymoron: Irish optimism,” Mr Biden told Israeli Prime Minister Benjamin Netanyahu when they met on the side-lines of last year’s UN gathering.

US President Joe Biden addresses the 79th session of the United Nations General Assembly (Julia Demaree Nikhinson/AP)

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, Mr 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 Mr Biden’s presidential legacy.

Israel and Hezbollah traded strikes again on Tuesday as the death toll from a massive Israeli bombardment climbed to nearly 560 people and thousands fled from southern Lebanon.

It is 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.

President Joe Biden walks out of the White House to board Marine One on the South Lawn in Washington (Mark Schiefelbein/AP)

Mr Biden has seemed more subdued in recent days about the prospects of Israel and Hamas agreeing to a temporary ceasefire and hostage deal. But he insists that he has not given up.

“If I ever say it’s not realistic then I might as well leave,” Mr 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.”

Mr Biden, in his address, is also expected to address ongoing Western support for Ukraine in its war with Russia.

He 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.

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

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

So far Mr Zelensky has not persuaded the Pentagon or White House to loosen those restrictions. The Defence Department has emphasised 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 US and its Nato allies if they allow Ukraine to use the long-range weapons.

Mr Biden and Ms Harris are scheduled to hold separate meetings with Mr Zelensky in Washington on Thursday. Ukrainian officials were also trying to arrange a meeting for Mr Zelensky with Mr Trump this week.