A large-scale Russian missile and drone attack damaged power plants and caused blackouts for more than a million Ukrainians on Friday morning, in what Ukrainian officials said was one of the war’s largest assaults on energy infrastructure.

At least three people were killed in the assault, and 15 others were injured, according to the office of Ukraine’s general prosecutor.

The strikes came as ​the Kremlin escalated its rhetoric over the conflict, saying that Russia was “in a state of war” in Ukraine — and moving beyond the euphemism “special military operation” — because of the West’s heavy involvement on the Ukrainian side.

In Kharkiv, Ukraine’s second-largest city, traffic lights were not working and the water supply was disrupted. A fire raged at the country’s largest hydroelectric dam, in the southeastern city of Zaporizhzhia. A few dozen miles to the southwest, a power line supplying a Russian-occupied nuclear power plant was temporarily knocked out.

“The enemy is now launching the largest attack on the Ukrainian energy sector in recent times,” Herman Halushchenko, Ukraine’s energy minister, said on Facebook. “The goal is not just to damage, but to try again, like last year, to cause a large-scale failure of the country’s energy system.”

The Ukrainian Air Force said that Russia had launched 63 Iranian-made “Shahed” attack drones and 88 missiles in the assault, including hypersonic weapons that fly at several times the speed of sound. The air force said it had shot down most of the drones but fewer than half of the missiles, a low interception rate compared with previous assaults that may reflect Ukraine’s dwindling air-defense stocks.

“Russian missiles have no delays, unlike aid packages for Ukraine,” President Volodymyr Zelensky said on social media, an apparent reference to the $60 billion in military assistance for Ukraine that Republicans in the United States Congress have held up for months.

“‘Shahed’ drones have no indecision, unlike some politicians,” Mr. Zelensky added.

Russia nonetheless complained on Friday about the United States’ assistance to Ukraine in the two years of war.

Since Moscow’s full-scale invasion began in 2022, the Kremlin has insisted that it was conducting a “special military operation.” The country’s communications watchdog ordered Russian news media outlets not to describe the hostilities as an “invasion” or a “declaration of war.”

But Russian officials including President Vladimir V. Putin have occasionally used the word war in reference to the conflict, mostly to insist that Russia has been fighting a Western coalition. And in an interview published on Friday in a hawkish pro-Kremlin tabloid, the Kremlin’s spokesman, Dmitri S. Peskov, attempted to explain the change.

“Yes, it started as a special military operation, but as soon as this grouping was formed, when the collective West became a participant in this one the side of Ukraine, it became a war for us,” he said. “I am convinced of that,” he added. “And everyone should understand that for their internal mobilization.”

The assault on Friday was reminiscent of Russia’s air campaign against the Ukrainian energy grid during the first winter of the war, which plunged Kyiv into cold and darkness. The Ukrainian authorities had warned that Russia was likely to repeat that campaign this winter, but instead Moscow’s air attacks had so far mostly targeted industrial and military facilities.

Friday’s attack was Russia’s second large-scale air assault in two days. A missile attack on Kyiv on Thursday injured at least 13 people and damaged several buildings.

The latest assault began shortly after midnight, when Russian forces launched dozens of attack drones against several Ukrainian regions, according to Ukraine’s air force. Then, around 3 a.m., Russian fighter jets fired cruise missiles, followed by ballistic missiles and then hypersonic Kinzhal missiles, one of the most sophisticated weapons in Russia’s arsenal.

The complex barrage appeared designed to overwhelm Ukrainian air defenses, following a strategy used in previous Russian air assaults. Ukraine’s air force said it had not managed to shoot down any of the Kinzhal missiles.

Missile strikes on power facilities caused outages in seven Ukrainian regions, according to Ukrenergo, the national electricity company, prompting the country to receive urgent energy assistance from Poland, Romania and Slovakia.

Volodymyr Kudrytskyi, the head of Ukrenergo, said that the attack was bigger than those targeting energy infrastructure during the first winter of the war. Oleksiy Kuleba, the deputy head of Ukraine’s presidential office, said that hundreds of thousands of homes had temporarily lost power, affecting some 1.2 million residents.

Mr. Kuleba said that “blackout schedules” had been introduced in several regions to “preserve the power system” during repairs.

Particularly affected was the eastern city of Kharkiv, where about 15 explosions were heard, according to Mayor Ihor Terekhov. A pumping station was hit, hampering the city’s water supply, and electric trams and buses were not functioning.

“The city is almost completely without electricity,” Oleh Syniehubov, the head of the regional military administration, said in the early morning. He said that 700,000 of the region’s residents had no electricity as of 9 a.m.

In the southern city of Zaporizhia, the Dnipro hydroelectric power plant suffered damage to its structure, including a large dam. Photos and videos posted online showed fire and smoke billowing from the plant, and the local authorities said that the road across the dam had been closed. Ihor Syrota, the head of Ukrhydronenergo, the state company that owns Ukraine’s hydroelectric plants, said that there was no risk of a breach, but that an electricity-generating unit was in critical condition.

Attacks on power installations were also reported in the western regions of Vinnytsia, Lviv and Ivano-Frankivsk. Airstrikes on these areas have been rare during the war.

Ukraine invested in protecting its energy infrastructure after the first winter of the war, building multilayered fortifications that included sandbags, concrete walls and cages filled with rocks. But the country’s energy system remains hobbled.

Oleksandra Mykolyshyn contributed reporting from Kyiv.