KYIV — President Zelensky’s welcome of Western leaders to Kyiv Saturday marks the second anniversary of Russia’s invasion, as Ukrainian forces run low on ammunition and weaponry and foreign aid hangs in the balance.

Mr. Zelenskyy posted a video from the Hostomel airfield together with Prime Ministers Meloni of Italy, De Croo of Belgium, Trudeau of Canada, as well as the European Commission president, Ursula von der Leyen.

“Two years ago, here, we met enemy landing forces with fire; two years later, we meet our friends and our partners here,” Mr. Zelensky said at the airport just outside Kyiv, which Russian paratroopers unsuccessfully tried to seize in the first days of the war.

The Western leaders arrived shortly after a Russian drone attack struck a residential building in the southern city of Odessa, killing at least one. Three women also sustained severe burns in the attack Friday evening, a regional governor, Oleh Kiper, wrote on his social media account. Rescue services combed through the rubble looking for survivors.

Italy, which holds the rotating presidency of the Group of Seven leading economies, announced that the G7 would meet virtually on Saturday with Mr. Zelensky and would adopt a joint statement on Ukraine.

“More than ever we stand firmly by Ukraine. Financially, economically, militarily, morally. Until the country is finally free,” Mrs. von der Leyen said in a post on X, formerly Twitter.

On the front line in the eastern Donetsk region, Ukrainian soldiers pleaded for ammunition. “When the enemy comes in, a lot of our guys die. … We are sitting here with nothing,” a senior officer in an artillery battery, Volodymyr, 27, said.

“In order to protect our infantry … we need a high number of shells, which we do not have now,” a commander of an artillery unit, Oleksandr, 45, said. The two officers only gave their first names, citing security concerns.

In a message on the war’s second anniversary, Colonel General Oleksandr Syrskyi, the commander-in-chief of Ukraine’s armed forces, thanked Ukrainian soldiers for their sacrifices and Western allies for their support, saying, “Every projectile, every tank, every armored vehicle is, first of all, saving the life of a Ukrainian soldier.”

Earlier this month, Mr. Zelensky fired Ukraine’s top military commander, Valerii Zaluzhnyi, and replaced him with General Syrskyi, marking the most significant shakeup of top brass since the full-scale invasion.

Authorities also pointed to successes, including the downing of a Russian early warning and control aircraft Friday. If confirmed, it would mark the loss of the second such aircraft in just over a month. The Ukrainian military says Russia uses the aircraft to direct missile attacks.

The war has also come to Russia. Drones hit a steel plant in the Lipetsk region in southern Russia Saturday, causing a large fire, the regional governor, Igor Artamonov, said, adding that there were no casualties. Independent Russian press said the Novolipetsk Metallurgical Plant is the largest steel plant in Russia.

Videos shared on Russian social media showed several fires burning at the plant, and an explosion could be heard. An independent Russian news outlet, Mediazona, said Saturday that about 75,000 Russian men died in 2022 and 2023 fighting in the war.

A joint investigation published by Mediazona and another independent Russian news site, Meduza, indicates that the rate of Russia’s losses in Ukraine is not slowing and that Moscow is losing about 120 men a day. Based on a statistical analysis of the recorded deaths of soldiers compared with a Russian inheritance database, the journalists said about 83,000 soldiers are likely to have died in the two years of fighting.

According to Mediazona and Meduza’s analysis, regular Russian troops sustained the heaviest losses in the first months of the war. After prisoners were offered their freedom in exchange for fighting and after President Putin ordered a partial mobilization, those groups started to sustain more casualties, particularly in the early months of 2023.

A somber mood hangs over Ukraine as the war against Russia enters its third year and Kyiv’s troops face mounting challenges on the front line amid dwindling ammunition supplies and personnel challenges. Its troops recently withdrew from the strategic eastern city of Avdiivka, handing Moscow one of its biggest victories.

Russia still controls roughly a quarter of the country after Ukraine failed to make any major breakthroughs with its summertime counteroffensive. Meanwhile, millions of Ukrainians continue to live in precarious circumstances in the crossfire of battles, and many others face constant struggles under Russian occupation. Most are waiting for a Ukrainian liberation that hasn’t come.

The president’s wife, Olena Zelenska, said Saturday that more than 2 million Ukrainian children have left the country since the war began and that at least 528 have been killed. “The war started by Russia deliberately targets children,” she said.

Britain has pledged an additional $10.8 million of humanitarian aid to Ukraine, bolstering efforts to provide medical care, food, and basic services to residents as the nation marks the second anniversary of Russia’s invasion.

About 14.6 million people, or 40 percent of Ukraine’s population, need assistance, with many left homeless or without adequate access to food, water, and electricity, Britain’s Foreign Office said in announcing the aid.

In Congress, Republicans have stalled $60 billion in military aid for Kyiv, desperately needed in the short term. The EU recently approved a $54 billion aid package for Ukraine meant to support Ukraine’s economy, despite resistance from Hungary.

President Biden tied the loss of the defensive stronghold of Avdiivka in the Donetsk region after months of grueling battles to the stalled aid. Fears have since spiked that Ukrainian forces will face similar difficulties across other parts of the 620-mile front line as they come under mounting pressure from Russian assaults.

Despite a heavy crackdown on dissent, some Russians marked the anniversary by laying flowers at Moscow monuments or holding anti-war signs in the streets. According to a Russian rights group that tracks political arrests and provides legal aid, OVD-Info, at least five people were arrested at Moscow on Saturday while holding signs saying “No to war” or attending a weekly demonstration calling for the return of mobilized Russian soldiers from Ukraine.

Police also detained a young woman who brought flowers in Ukraine’s national colors, blue and yellow, to a Moscow monument to victims of political repression, OVD-Info reported.

By Susie Blann. Alex Babenko contributed.