Wars in Middle East, Ukraine poised to dominate high-stakes UNGA: ANALYSIS

As the 79th United Nations General Assembly kicks off in New York this week, it brings together more than 100 world leaders for a high-profile summit focused on addressing the world's most pressing challenges.

This year's annual meeting also gave President Joe Biden an opportunity to deliver his swan song on the international stage during a speech to world diplomats Tuesday morning.

However, the bulk of the Biden administration's diplomatic agenda for the gathering is expected to play out behind the scenes in critical sideline meetings, as U.S. diplomats race against the clock to contain the spreading conflict in the Middle East and ensure Ukraine can stave off Russian advances.

All eyes on the Middle East

Although the U.N.'s headquarters are half a world away from the conflict in the Middle East, the chief area of concern for many of the body's members will be Israel's military campaign in Gaza against Hamas and its intensifying Israeli strikes on Lebanon.

Israel appears to have opened a new chapter in its battle against Hezbollah, a U.S.-designated terrorist organization operating in Lebanon, by infiltrating the group's communication system with exploding devices and ramping up airstrikes targeting its top officials.

While U.S. officials have been working to prevent the Israel-Hamas war from spreading through the region for nearly a full year, the Biden administration's response to the latest escalation has been relatively muted. Secretary of Defense Lloyd Austin has held multiple calls with his Israeli counterpart, but neither he nor Secretary of State Antony Blinken have imminent plans to travel to the Middle East and cool tensions.

Notably, the State Department has also not publicly detailed any recent calls between Blinken and Israeli officials.

However, the U.N. General Assembly will bring the matter -- as well as Israel's ongoing war in Gaza -- to the administration's doorstep. U.S. officials are expected to hold private meetings as they plot their next steps, but Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas are also scheduled to address the General Assembly later in the week, placing a spotlight on the conflicts' deep, polarizing roots.

Iran is the chief financial backer of Hamas and Hezbollah, and the country's newly elected president, Masoud Pezeshkian, is slated to speak on Tuesday.

The Biden administration is also expected to quietly attempt to advance a deal to secure a cease-fire in Gaza and the release of the hostages held by Hamas. But U.S. officials are not optimistic, as the latest round of negotiations orchestrated by American, Qatari and Egyptian mediators have been stalled for weeks.

At the beginning of the month, Blinken promised that a new U.S peace proposal for Gaza would be presented to Israel and Hamas "in the coming days." So far, that proposal has yet to materialize, and criticism faulting the administration for the lack of a "Plan B" to end the war has grown louder.

Through the course of the Israel-Hamas war, the U.N. has proven to be a politically tricky venue for the Biden administration. As a permanent member of the body's Security Council, the U.S. has used its outsized power to veto resolutions calling for a cease-fire in Gaza as well as a bid to elevate Palestine, a U.N. observer state, to a full member status.

In each instance, American diplomats offered explanations on why they rejected the proposals -- arguing in the measures ran counter to ongoing peace efforts. Still, the public votes have opened the U.S. to scrutiny and often forced the administration to stake a position that ran counter to most U.N. members.

A peace plan for Ukraine

During Biden's first speech to the General Assembly as president in 2021, he did not mention Ukraine once.

Now, supporting the country and its fight against Russia's full-scale invasion has become a defining cause of the Biden administration. But the war, now in its third year, shows no sign that it is nearing a resolution.

Ukraine's President Volodymyr Zelenskyy arrived in New York on Sunday and says he will present what he calls a "victory plan" to the U.S. and other allies of Ukraine this week.

Zelenskyy's proposal consists of five different points and includes specific projections on additional military assistance Kyiv says will be necessary to force Russia to end its aggression once and for all, according to a source close to the Ukrainian president.

"We have two paths -- either through force or diplomacy," the source told ABC News, adding that the plan doesn't include any concessions for Moscow.

U.S. officials say that Russian leader Vladimir Putin has yet to signal a genuine willingness to negotiate with Ukraine, much less lay down arms entirely. But the administration's ambassador to the U.N., Linda Thomas-Greenfield, spoke favorably about Zelenskyy's proposal.

"We think it lays out a strategy and a plan that can work. And we need to see how we can promote that as we engage with all of the countries' heads of state who will be here in New York," she said. "Hopefully we can make some progress on that.

It's still unclear how Zelenskyy's plan differs from the 10-point peace formula he outlined at last year's gathering, which did not substantially boost support for Ukraine.

The Biden administration has promised that Ukraine's success does not rest on the shoulders of any one country, but rather its broad network of allies. But as the U.S. presidential election looms, officials can only promise so much in terms of U.S. backing.

Vice President Kamala Harris has vowed she will "stand strong with Ukraine" if elected, while Republican nominee Donald Trump has expressed skepticism -- calling Zelenskyy "the greatest salesman." And no matter who wins the White House in November, they will be largely reliant on Congress to appropriate the funds.

Haiti, Venezuela and beyond

The Biden administration also hopes to draw attention to a host of other issues during the General Assembly, including one where the U.N. already is playing a direct role: the ongoing turbulence in Haiti.

The U.N. authorized a Kenyan-led security mission to address gang violence roiling the island nation in 2023. Police officers have been deployed for just over three months, but they have made only modest progress toward restoring law and order.

With the mission's U.N. mandate set to expire next month, U.S. officials say a priority for the week will be shoring up support for sustained intervention -- possibly by transitioning it to a full-fledged U.N. peacekeeping operation.

Thomas-Greenfield also said the U.S. will draw attention to another issue in the Western Hemisphere -- Venezuelan strongman Nicolas Maduro, who the Biden administration says is clinging to power even though he lost the presidential election in July.

"We do want to engage on this in New York," she said. "I know that there are countries who will be raising this as a concern, and we will have meetings related to that."

Additionally, the Biden administration will also seek to draw support for its plan to expand the U.N. Security Council by adding two permanent seats for African nations.