Some of the missiles were launched from Belarus, whose leader is meeting Saturday with the Russian president.
From the skies above Belarus to the north and the waters of the Black Sea to the south, Russian forces unleashed a fusillade of cruise missiles across Ukraine on Saturday, Ukrainian officials said, in one of the most widespread and coordinated aerial assaults in weeks.
Even as Russia pounded civilian and military infrastructure from the air, fierce fighting raged on the eastern front, where Russian forces pressed to cut off the supply lines for thousands of Ukrainian soldiers.
The Ukrainian military said that Russian warplanes had attacked Ukrainian positions near the eastern city of Lysychansk, the last urban stronghold still under Ukrainian control in the eastern Luhansk Province, as Russian forces pressed to encircle the city.
The missile strikes came hours before President Vladimir V. Putin of Russia was scheduled to meet with President Aleksandr G. Lukashenko of Belarus in St. Petersburg. Belarusian forces are also once again conducting military drills near the border with the Kyiv region, raising tensions and putting the Ukrainian authorities on high alert.
Ukraine’s military intelligence agency called the Russian assault “a large-scale provocation of Russia for the purpose of further dragging Belarus into the war against Ukraine.” Western military analysts say it is unlikely that Belarus would join the Russian war effort, but Mr. Lukashenko’s hold on power is dependent on the Kremlin’s support, limiting his room for political maneuver.
President Biden was traveling on Saturday to Germany, where he would join the leaders of the world’s wealthiest democracies — known as the Group of 7 — to bolster Western resolve in supporting Ukraine in the face of the growing economic toll the war is taking on their nations.
Even as Ukraine faces perhaps its toughest moment on the battlefield since the early weeks of the war, the commander of its military, Gen. Valeriy Zaluzhnyi, released a slickly produced video to celebrate the first battlefield use of advanced multiple-launch rocket systems from the United States. He said the weapons were being used to hit “military targets of the enemy on our, Ukrainian, territory.”
But the Russian missile strikes offered a potent reminder of the vast destructive power of the arsenal at Moscow’s disposal, which has been both directed at military targets and used to indiscriminately pummel cities and towns.
The mayor of the embattled southern port city of Mykolaiv, which has been under attack from Russian forces since the start of the war, called for “everyone who wants to survive” to leave, because “it’s not clear when all this will be over.”
Speaking in an interview with Radio Liberty, he said that the city was being shelled daily, and that “around 80 percent of those munitions are cluster munitions” fired from Russian multiple-launch rocket systems.
Already about half of Mykolaiv’s prewar population of 480,000 has fled. Among those remaining, many are older, and about 80 percent of them survive on food and clothes distributed by aid organizations.
The Russian strikes on Saturday also hit areas of the country that have been relatively quiet in recent weeks. Even in western and northern regions, where the wail of air alarms had become more sporadic, they rang out numerous times in less than 48 hours to signal that missiles had been fired within striking distance.
Dozens of the missile strikes were launched by Russian aircraft in Belarusian airspace overnight, according to a Belarusian monitoring group, Belarusian Guyun, which has been detailing Russian actions since the start of the war.
The Ukrainian military intelligence agency said that six Russian Tu-22M3 strike bombers took off from the Shaykovka airfield in Russia’s Kaluga region, flying over Smolensk, before entering Belarusian airspace. Once they were within about 30 miles of the Ukrainian border, the agency said, they fired at least 12 cruise missiles before returning to Russian airspace. The missiles struck targets in the Kyiv, Chernihiv and Sumy regions, the military said.
Local Ukrainian officials reported more missiles that they said appeared to have been launched from Belarus, including a barrage of 24 missiles that hit the outskirts of Zhytomyr, a city about 80 miles west of Kyiv.
The toll from overnight strikes across the country was not immediately clear, and the Ukrainians seldom release details about strikes on military installations. But Vitaly Bunechko, the governor of the Zhytomyr region, said that at least one soldier had been killed and that another had been wounded.
In the Chernihiv region directly east of Kyiv, Vyacheslav Chaus, the area’s governor, said that a “massive missile strike” from Belarusian territory had destroyed infrastructure in the village of Desna, where Ukrainian forces also have a military installation.
The Ukrainians said their air defenses had shot down two missiles among a salvo of six launched from naval vessels on the Black Sea, with the remaining four hitting a “military object” in the Yavoriv area, the site of a military training base in Lviv region. Four people were injured, said Maksym Kozytskyi, the region’s governor.
The Yavoriv district has been targeted several times since the start of the war, including a major attack in March that killed and injured dozens.
The attacks came as Ukraine is on a heightened state of alert as the Belarusian Armed Forces hold “mobilization” drills near Ukraine’s northern border. The drills threaten to aggravate tensions in an already volatile region and have prompted Ukraine to put its border guards on high alert.
In the early stages of the war, Belarus allowed Mr. Putin to use its territory for Russian troops to stage a shock-and-awe operation to try to capture Kyiv. The plan failed spectacularly, but with Russia now bogged down in a grinding war of attrition in Ukraine’s east, Moscow would benefit from any help Mr. Lukashenko could provide.
Ukrainian officials and Western observers think it is highly unlikely that Belarus, a former Soviet republic of 9.4 million people, will directly join the war at this time, given the risks of provoking social unrest at home and undermining Mr. Lukashenko’s grip on power. Nevertheless, analysts believe Mr. Lukashenko, an autocrat beholden to the Kremlin, is desperately trying to show his value to Mr. Putin.
And some analysts believe it is only a matter of time before pressure from Mr. Putin forces Mr. Lukashenko to take more direct action in the war, pushing him into an existential dilemma. Joining the conflict could undermine his support at home, but if he does not do Mr. Putin’s bidding, the Russian leader could retaliate by taking steps to force him from office.
Roger Cohen contributed reporting.