In Canada, Zelensky warns cutting military aid would only lead to more Russian aggression.

Mr. Zelensky added that while Ukraine is grateful for all the military and financial assistance it has received, nevertheless “the largest price, this is something that Ukraine has paid because we are paying with the lives of our people.”

Earlier Mr. Zelensky told a special session of Parliament that Russia is conducting a genocide in Ukraine.

“It is genocide, what Russian occupiers are doing to Ukraine,” Mr. Zelensky said. “It is not just about an ordinary conflict. It is about saving lives of millions of people.”

“This Russian aggression must end with our victory so that Russia will never bring back genocide to Ukraine,” he added.

The speech to the joint session of Canada’s House of Commons and Senate was the most widely anticipated event in his first trip to the country since Russia’s full-scale invasion of Ukraine in February 2022. The audience, which included guests as well as lawmakers, repeatedly interrupted Mr. Zelensky with standing ovations.

Mr. Zelensky thanked Canada for its military and humanitarian assistance as well as its support for Ukraine’s entry into NATO. He also urged Western nations to seize Russian assets and use them as reparations for Ukraine as well as to bring “Russia to justice for the crime of aggression itself.”

The address followed a meeting with Prime Minister Justin Trudeau, who has been a particularly strong supporter of Ukraine, reflecting a consensus among Canadians. His country has the largest population of expatriate Ukrainians aside from Russia, and Mr. Trudeau’s government has provided about $3.7 billion in financial assistance to Ukraine and an additional $1.3 billion in military aid. About 175,000 Ukrainians have found refuge in Canada since the Russian invasion began.

The Canadian prime minister greeted Mr. Zelensky at a 19th-century building in Canada’s Parliamentary complex that has become the temporary home of the House of Commons, which is being renovated.

Before Mr. Zelensky spoke, Mr. Trudeau told the special Parliamentary session that Ukraine’s fight is a battle for a world governed by rules and laws.

“President Zelensky, you and the Ukrainian people are holding the rules-based order in the balance,” Mr. Trudeau said. “You are on the front lines, not just the fight for Ukraine.”

Mr. Trudeau characterized the conflict as “a challenge on a generational scale, a challenge that history will judge us on, a challenge we must confront with lionhearted courage.”

The prime minister announced that Canada will expand its aid by adding 50 Canadian-made armored vehicles, including some that will be equipped as field ambulances, assistance that will cost about $480 million. Mr. Trudeau told the news conference that a previously announced $370 million in military assistance will include pilot and maintenance crew training for the F-16 jets that Ukraine is receiving from Denmark and the Netherlands, 35 drones with high-resolution cameras, tank maintenance and small arms ammunition.

Mr. Trudeau said that Canada is also working with other Group of 7 industrialized nations to examine further Russian asset seizures, including $200 billion to $300 billion in Western banks that belong to Russia’s central bank.

Mr. Zelensky, who spoke to Canada’s Parliament virtually last year, joined a small list of leaders who have twice addressed it, a group that includes Nelson Mandela, Ronald Reagan and Winston Churchill.

Mr. Zelensky left Ottawa for Toronto and a private meeting with businesspeople. Then in a military drill hall after a fiery introduction from Mr. Trudeau, Mr. Zelensky was met by a cheering invitation-only crowd dominated by Ukrainian Canadians, many of them in traditional clothing. He thanked their ancestors for maintaining Ukrainian culture when the country was under Soviet domination.

“The victory will be ours,” he said. “I have no doubt.”

A Ukrainian attack targets the headquarters of the Russian Black Sea Fleet in Crimea.

Ukraine’s military said in a brief statement that its forces had struck the Black Sea Fleet headquarters.

The Ukrainian military has long maintained that the war cannot be won without taking aim at Russian assets and operations in Crimea, which Moscow illegally annexed in 2014. In recent weeks, Ukraine has sharply accelerated the pace of strikes on the peninsula, which Russia’s military uses as a hub, stockpiling fuel, ammunition and other supplies to be funneled to the battlefields in southern Ukraine.

“There’s a lot of military assets there which are taking part in the war,” Samuel Bendett, a Russian weapons analyst at the Center for Naval Analysis, said in an interview. He noted that, in addition to the Black Sea Fleet, the peninsula also houses attack planes and helicopters, as well as infantry bases.

Mikhail Razvozhayev, the governor of Sevastopol, on Crimea’s southern coast, said in a statement that firefighters were battling the blaze at the headquarters. He added that no one had been injured outside the building and that nearby civilian infrastructure had not been damaged.

Mr. Razvozhayev initially warned that another attack was possible. He later said that there was no longer any threat but urged residents to avoid Sevastopol’s city center, where the headquarters building is.

Oleg Kryuchkov, an official with the Russian-installed authorities in Crimea, said that debris from a downed missile had also sparked a grass fire in Bakhchysarai, a town about 20 miles northeast of Sevastopol.

Last week, another attack targeting the headquarters of the Black Sea Fleet damaged two ships and triggered a large blaze at a sprawling naval shipyard that plays a critical role in the Russian war effort.

On Wednesday, Ukraine’s military said its missiles took out a command post for the Black Sea Fleet in the village of Verkhnesadovoye, a few miles north of Sevastopol’s city center. Satellite images analyzed by The New York Times showed damage to the command post.

Arijeta Lajka contributed reporting.

Cluster munitions, shunned by much of the world, remain on the list of U.S. military hardware going to Ukraine.

And on Thursday, just over two months after the first shipment was sent — and as President Volodymyr Zelensky of Ukraine was visiting the White House — the Biden administration announced that the United States would send another batch of cluster weapons.

The term “cluster munitions” covers a wide class of weapons including rockets, bombs, missiles and artillery projectiles that break open and scatter smaller explosives. Their failure rate is high, which means they can potentially harm civilians after the fighting ends.

More than 100 countries — excluding the United States, Russia or Ukraine — have signed the 2008 Convention on Cluster Munitions, which promised not to make, use, transfer or stockpile the weapons. Since then, nearly all global stockpiles have been destroyed, according to the Cluster Munition Coalition.

“There’s just not a responsible way to use cluster munitions,” said Brian Castner, the weapons expert on Amnesty International’s Crisis Response Team.

Ukrainian leaders have said that the weapons are important for countering Russian forces, though they have acknowledged their potential for causing indiscriminate harm. As a condition of receiving cluster munitions from the United States, Mr. Zelensky and senior Ukrainian defense officials pledged to avoid firing the weapons into civilian areas.

Whether the munitions have proved useful on the battlefield remains a matter of debate. Some Ukrainian soldiers have said in interviews that the U.S.-supplied munitions have been an efficient and necessary addition to their arsenal. But other soldiers disagree, saying they have been largely ineffective against dug-in Russian defensive positions. The cluster weapons have been used mostly when enemy infantry are already flushed out of their fortified trenches.

American officials maintain that the weapons have been used successfully to take out Russian troops, artillery systems, air defenses, ammunition depots, radar stations and vehicles. But some experts say that the weapons have their limits, and other analysts have said that they have not yet provided any decisive effects on the battlefield.

Even before American cluster munitions arrived, Russia and Ukraine had both used the bomblets on the battlefield. Russia has frequently fired cluster bombs into residential areas, while Ukraine has used them against Russian targets on its soil, creating an environment that could harm Ukrainians after the war ends.

Zelensky predicts during U.S. visit that Ukraine will win back Bakhmut.

Ukraine has been waging a counteroffensive since June to drive Russian forces from occupied areas in the country’s south and east. However, American and other Western officials have said that Ukraine has misallocated its forces in the counteroffensive, putting more troops near Bakhmut and other cities in the east than are near Melitopol and Berdiansk in the south — both far more strategically significant fronts.

On Sunday, Ukraine’s military said that it had retaken Klishchiivka, a village outside Bakhmut. The retaking of Klishchiivka may help Ukraine apply pressure to the Russian forces holding Bakhmut, which Moscow has devoted resources to defending even though it has been reduced to rubble.

Mr. Zelensky also said Thursday that Ukraine would not stop its counteroffensive this winter and hoped to take advantage of what he considered Russian weaknesses.

Ukrainian armored vehicles breach some Russian defenses, reflecting slight progress in a halting counteroffensive.

Earlier this summer, Ukrainian tanks had broken through a less formidable layer of defenses, and infantry had pierced a second line, seen as Russia’s main anti-tank barrier.

The breach, a swath of farm fields and tree thickets a mile or so wide, is a crucible of concentrated Russian and Ukrainian artillery fire, littered with blown-up vehicles and dotted with craters. It sits near Robotyne, a village that Ukrainian forces captured several weeks ago.

The recent breakthrough, shown in unverified videos published Thursday, suggested that weeks of bloody infantry fighting had secured the breach sufficiently to move heavy weaponry forward. That would be a positive step for Ukraine in its campaign to drive Russian forces from the south. More Russian minefields and anti-tank barriers remain ahead.

The U.S. is expanding F-16 patrols over Romania amid concerns about drone debris.

It remains unknown how the debris got there, including whether it landed by accident. Since the collapse of a deal this summer that had allowed Ukraine to safely ship its grain through the Black Sea, Russia has repeatedly attacked Ukrainian ports — including those that sit across the Danube River from Romania.

While Romania’s defense minister, Angel Tilva, has said the wreckage does not pose a threat, Romanian authorities have determined that at least some of the debris is similar to the drones used by the Russian army. If that is proven, it could amount to a violation of Romania’s sovereignty, according to President Klaus Iohannis, who has raised the issue with Jens Stoltenberg, the NATO secretary general.

“Luckily so far nobody has been hurt and no real damage occurred, but it doesn’t mean that it didn’t matter,” Mr. Iohannis said in remarks Thursday in New York, adding that any “spillover” from the war to Romania was “fully unacceptable.”

While the drones are not directed at Romania, he said, the fact that debris has been found in the country “is a real problem and it has to be addressed.”

But Romania has not shown any sign that it might invoke Article 5 of the NATO treaty, the cornerstone of the alliance’s mutual defense pact, that could expand the war.

The alliance and its member states are flying air surveillance and air policing missions over NATO territory, territorial waters and international waters over the Black Sea, but are careful not to stray into the war zone. Amid mounting tensions in the Black Sea, NATO said in July that it had increased the number of such flights.

Here are some of the highlights of President Zelensky’s trip to the U.S.

“The goal of the present war against Ukraine is to turn our land, our people, our lives, our resources into a weapon against you, against the international rules-based order,” Mr. Zelensky told the dignitaries. He added that Russia was weaponizing essentials like food and energy “not only against our country, but against all of yours, as well.”

A scathing speech

Speaking to the Security Council, Mr. Zelensky criticized the United Nations for failing to prevent or resolve conflicts like the one destroying his country and called for Russia to be stripped of the veto power it has as a permanent member of the council.

“Ukrainian soldiers are doing with their blood what the U.N. Security Council should do by its voting,” Mr. Zelensky said on Wednesday, adding that “veto power in the hands of the aggressor is what has pushed the U.N. into deadlock.” Any proposed change to the veto rule would itself be subject to a veto.

Lobbying Washington for aid

The Ukrainian president met with lawmakers on Capitol Hill on Thursday, where dozens of Republicans have voiced their opposition to sending more weapons to Ukraine. “If we don’t get the aid, we will lose the war,” Mr. Zelensky said, according to Chuck Schumer, the Senate majority leader and a Democrat.

Mr. Zelensky appeared to have made little immediate progress in persuading the Republican leadership of the House of Representatives to approve an additional $24 billion in military and humanitarian aid to Ukraine.

A meeting with Biden

Mr. Zelensky finished his visit at the White House, where he met with President Biden on Thursday after receiving a $325 million air-defense package from existing funding. Mr. Biden also said that next week the U.S. would begin shipping over Abrams tanks, which Ukraine has long sought and which the Biden administration in January agreed to donate. Mr. Biden acknowledged that he had little choice but to have faith in a bipartisan breakthrough for continued support for Ukraine.

“I’m counting on the good judgment of the United States Congress,” Mr. Biden said. “There’s no alternative.”

A cargo ship loaded with Ukrainian grain reaches Romanian waters.

For a year, until July, Ukraine was able to export directly from three of its ports, including Odesa and Chornomorsk, to Turkey and through the Bosporus under a deal brokered by Turkey and the United Nations.

Moscow terminated that deal and warned that it would consider any ship approaching a Ukrainian port to potentially be carrying military cargo. It also began a campaign of missile strikes against Ukraine’s Black Sea and Danube River ports, and a Russian patrol ship fired warning shots and then boarded a cargo vessel in the Black Sea in August.

Ukraine, determined to continue with sea exports, is now attempting to establish a new route in which ships sail along the coast to the maritime border with Romania, a country that is a member of the North Atlantic Treaty Alliance. From there, they will continue to the Bosporus. The Aroyat passed Romania’s maritime border and was heading south toward Bulgarian waters, according to MarineTraffic, a website that tracks global shipping using satellite data.

On Tuesday, a cargo ship loaded with a much smaller quantity of grain departed from Chornomorsk and reached the Romanian maritime border without apparent incident, in an initial test of that route. By Friday, the ship, the Resilient Africa, had reached port in Istanbul, according to MarineTraffic.

Whether Ukraine can fully establish its new grain route depends on several factors, including the willingness of private shipping companies to accept an elevated risk, particularly while the vessels are in port or in Ukrainian waters, shipping experts say.

The greatest risk is a further escalation of conflict in the Black Sea, which in recent months has become an increasingly central theater of the wider war between Moscow and Kyiv.

Ukraine and the U.S. work on boosting weapons production inside Ukraine.

Joint production would be potentially important for Ukraine’s economy and lucrative for defense industry contractors.

“This is a new level of our unity!” Mr. Zelensky said in his daily address to Ukrainians. He said the endeavor would build air defense systems, create jobs, and kick-start Ukraine’s shrunken defense industry, which under the Soviet Union had been one of its largest employers.

While in Washington, Mr. Zelensky presided over initial agreements brokered between Ukraine and American industry representatives from the Arizona Defense & Industry Coalition and the Utah Aerospace and Defense Association that he described as a move toward establishing U.S. defense production inside Ukraine.

The United States is just one among a growing pool of eager allies and foreign manufacturers that are looking to gain a financial foothold on Ukraine’s battlefield. Britain, Germany and others also are moving to bolster Ukraine’s defense industry, including by building joint manufacturing facilities in the country.

One of the first out of the gate was Rheinmetall, the German-based weapons production giant, which announced in May that it was teaming up with Ukraine’s state-owned Ukroboronprom to build armored vehicles and tanks inside Ukraine.

In late August, Britain-based BAE Systems said it had signed an agreement to explore manufacturing 105-millimeter light guns in Ukraine, though it did not make clear when that would start.

U.S. officials see the efforts as a step toward weaning Ukraine off the shipments of Western weapons it receives on a near-weekly basis, especially as political support in Washington and other world capitals for continuing the costly donations threatens to wane.

“For all of the armored vehicles, for all of the Bradleys, Strykers, all of the arms that Ukraine needs, their national defense production act really has to be implemented more aggressively,” Sen. Richard Blumenthal, Democrat of Connecticut and a member of the Armed Services Committee, said in an interview last month.

Otherwise, “our stockpiles and Ukraine’s supplies are going to be diminished dramatically and potentially exhausted,” Senator Blumenthal said. He noted that production sites would need to be protected, including with adequate air defenses, but “we’re going to be building those factories in Ukraine so that they have a much more dependable source.”

Last year, Ukraine was the world’s largest arms importer — a direct result of the military aid it has received since Russia’s full-scale invasion in February 2022, according to the Stockholm International Peace Research Institute, which tracks weapons transfers.

“I am sure the defense industry will become the backbone of security during the wartime,” Alexander Kamyshin said last month, predicting that it would be “the locomotive for economic revival after the war is over.”