Even as he embarked on his mission to confront skeptical voices, Zelensky still received a warm welcome inside the grand U.N. chamber. But in a possible sign of the challenges he faces in winning wavering leaders to his side, he delivered his address to a half-full house, with many delegations failing to show up to listen to what he had to say.

“Mass destruction is gaining momentum,” Zelensky said. “The aggressor is weaponizing many other things and those things are used not only against our country, but against all of yours as well, fellow leaders.”

He sought to connect global food shortages and rising prices for energy to Russia’s aggression against his country, drawing a link between the conflict and some of the problems that leaders of less wealthy nations say are being ignored as the United States and Europe focus their bandwidth on dealing with the fight.

And he said that at a moment when global warming is causing drought, extreme weather and human destruction, humanity could scarcely deal with a bloody war of choice on top of it all.

“When all of this is happening, a natural disaster in Moscow decided to launch a big war and kill tens of thousands of people. We have to stop it,” Zelensky said, declaring that respect for the rule of law and the U.N. Charter was important to all nations, not just his own.

Zelensky’s several-day visit to the United States was intended to take advantage of his powerful oratory to sway wavering voices. The trip started with a visit Monday to a New York military hospital where Ukrainian soldiers are being treated and will conclude Thursday with a visit to the White House and meetings with congressional leaders.

It was the Ukrainian leader’s first in-person trip to the United Nations since the war started in February 2022. At last year’s General Assembly, he delivered remarks from Ukraine by video link. At the time, Ukrainian troops were engaged in a lightning-quick operation that ousted Russian troops from the northeast Kharkiv region. He visited Washington in December, riding off that success after recapturing significant portions of the territory that Russia had taken early in its invasion.

This moment is trickier, after Ukrainian troops pressing a counteroffensive for months have not made the major advances Kyiv and its backers had hoped for. Still, Ukraine has shown its clear ability to hold back Russia and prevent major advances along the front lines. Instead, the war has evolved into a grinding battle of trenches, minefields, and artillery and rocket volleys. To wit, Russian forces launched an overnight missile and drone attack Tuesday that pummeled cities as far west as Lviv, where officials said a humanitarian aid warehouse was destroyed.

The U.N. General Assembly has voted overwhelmingly to condemn the invasion and demand respect for Ukraine’s borders but the Kremlin has ignored the calls for withdrawal of its troops.

Ukraine ousts more defense officials and decries grain ban by E.U. neighbors

Zelensky, a comedian and actor by profession, has proved to have formidable powers of persuasion on the world stage.

In a statement to The Washington Post previewing Zelensky’s visit to the United Nations and the United States, Ukrainian Foreign Minister Dmytro Kuleba said that his country had no better advocate.

“I’ve seen him at numerous international events and meetings, and I know he has a type of superpower, the capacity to really persuade people in person,” said Kuleba, who also traveled to New York.

Zelensky was also scheduled to attend a meeting of the U.N. Security Council and “hold a number of important bilateral talks,” Kuleba said, without providing further details. Zelensky, he said, will “put forward some very specific steps” that the United Nations can implement “to fortify the principle of territorial integrity.”

“We are now at a critical juncture in time, as Ukraine continues to advance on the battlefield,” Kuleba said, “and it is critical to sustain and strengthen worldwide support for Ukraine.”

Despite Kyiv’s claims of small and steady territorial gains, concerns have mounted in the West that the war could be hardening into a protracted, possibly years-long conflict. Such a scenario would potentially benefit Russia, which has a much larger military and larger population to draw soldiers from. It could also have grave economic repercussions internationally.

Despite Russia’s flagrant invasion of its neighbor, the deaths of thousands of soldiers and civilians, and allegations of war crimes by Russian troops, some countries in Asia, Africa and South America have been reluctant to enforce Western sanctions against Russia, for fear of disrupting their economic and diplomatic links with Moscow.

In the United States, some American lawmakers, particularly House Republicans, are questioning the high price tag of continuing economic and military support to Ukraine, estimated to be about $73 billion globally.

On Thursday, Zelensky will travel to Washington to meet President Biden — his second meeting at the White House since Russia’s invasion began — as well as Senate and congressional leaders and other top officials.

A web of trenches shows Russia fears losing Crimea

Ukrainian forces are making slow headway and suffering heavy losses in their counteroffensive, launched at the start of the summer, as they advance on entrenched Russian positions through heavily mined fields.

Last week, Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, said Ukrainian troops might have just “30 to 45 days” left before rain and freezing weather halt fighting until next year, although Ukrainian officials say fighting will not stop during the winter.

U.S. intelligence officials have also predicted that during this time, Ukraine will not reach the city of Melitopol, one of the key objectives of the counteroffensive this year.

On Monday, officials said Ukrainian troops had liberated the village of Klishchiivka in eastern Ukraine, located near the city of Bakhmut, which could provide a foothold for further advances. The news, while positive, also underlined the slow pace of Ukrainian troops’ progress.

The battlefield situation contrasts with that last December, when Zelensky made his previous trip to the United States, which also included a joint address to Congress. Then, Ukrainian forces had recently liberated Kherson in the south, the only regional capital that Russian forces managed to occupy.

On Tuesday, Ukraine’s air force said that Russian forces had launched 30 self-destructing drones and one ballistic missile overnight at targets across Ukraine.

More than half of the drones were directed at the western Lviv region, the head of the local regional administration, Maksym Kozytskyy, said on social media. Three warehouses in the city of Lviv were struck, including one belonging to Caritas-Spes Ukraine, a Roman Catholic humanitarian organization that is part of the Caritas Europa Federation.

Caritas employees “were unharmed,” the organization said in a statement, but “the warehouse with everything inside burned to the ground.” However, one person was killed in a strike on another warehouse, local officials said.

Denise Brown, the U.N. humanitarian coordinator for Ukraine, said in a statement that she condemned “in the strongest terms” the attack on the Caritas-Spes warehouse, which destroyed 300 tons of humanitarian aid.

“Attacks impacting humanitarian assets have escalated throughout the year and ultimately impact those who are suffering the horrific consequences of the war,” Brown said.

Lviv Mayor Andriy Sadovyi said the Lviv region had “practically no military facilities” and was used primarily as a production center and hub for humanitarian operations.

“Most likely, [the Russians] get satisfaction when they cause pain,” he said.

Stern and Morgunov reported from Kyiv. Isabelle Khurshudyan in Lviv and Kostiantyn Khudov in Kyiv contributed to this report.