Shelling killed at least five people on Saturday in the recently recaptured Ukrainian city of Kherson, hours after President Volodymyr Zelensky of Ukraine warned that another wave of Russian strikes could mar the Christmas holidays.
“With the approaching holiday season, Russian terrorists may become active again,” Mr. Zelensky said in his overnight address. “Therefore please heed the air-raid signals, help each other and always take care of each other.”
His comments came after Ukraine’s military warned on Friday that Russian ships carrying cruise missiles had entered the Black Sea for the first time since Dec. 16, when Moscow fired a barrage of missiles across Ukraine.
On Saturday morning, many people were out on the streets of Kherson when Russian forces shelled the center of the city, according to Kyrylo Tymoshenko, the deputy head of the president’s office. At least 35 people were wounded in addition to the five killed, he said on the Telegram messaging app.
Images from the scene of the attack showed several people and blood in the street and cars burning. Mr. Zelensky posted the photographs on his Telegram account, saying that they showed “the real life of Ukraine and Ukrainians.”
“In the morning, on Saturday, on the eve of Christmas, in the central part of the city,” he wrote. “These are not military facilities. This is not a war according to the rules defined. It is terror, it is killing for the sake of intimidation and pleasure.”
In addition to observing Eastern Orthodox Christmas on Jan. 7, Ukraine also celebrates Christmas as a national holiday on Dec. 25, in line with the Western calendar, particularly Roman Catholics in western Ukraine.
Kherson has been bombarded by Russian shelling since Ukrainian forces retook the city last month. Russian troops there withdrew east across the Dnipro River and have since fired hundreds of shells at the city from their new positions. Five people were killed and 17 others were wounded on Friday, Mr. Tymoshenkso said in an update on Saturday morning before the latest attack.
Overnight strikes also leveled a gymnasium and damaged houses in the southern region of Zaporizhzhia, according to local officials. No casualties were reported.
Russia’s war in Ukraine is now fought in two largely separate arenas: ground battles in the south and east, and a contest between Ukraine’s air defense systems and Russia’s cruise missiles and drones aimed at electrical infrastructure. Military analysts say the infrastructure-targeting campaign is intended to demoralize Ukrainians and push their government into a cease-fire that might allow Russia time to regroup and rearm for future offensives.
Since October, Russia has fired volleys of missiles and drones at Ukraine’s energy infrastructure in intervals of roughly a week to 10 days, according to Ukraine’s military intelligence chief. Most volleys have included around 75 missiles.
That tempo is likely set based on Russia’s weapons supply, Britain’s defense intelligence agency said on Saturday.
“Russia has likely limited its long-range missile strikes against Ukrainian infrastructure to around once a week due to the limited availability of cruise missiles,” the agency said in its daily update. “Similarly, Russia is unlikely to have increased its stockpile of artillery munitions enough to enable large-scale offensive operations.”
For weeks, Ukrainian officials have expressed concern that Russian forces could use neighboring Belarus as a launchpad for a new ground offensive, with Kyiv, Ukraine’s capital, a potential target.
But the director of Ukraine’s military intelligence agency said in an interview with The New York Times on Friday that while the possibility could not be entirely ruled out, a recent flurry of Russian military activity in Belarus was an attempt by Moscow to trick Ukraine into diverting soldiers from the active front line in the southeast of the country.
The Institute for the Study of War, a Washington-based research group, also said in its latest report that there was no evidence that Russia was preparing a strike force in Belarus, and that a renewed invasion from the country was “unlikely” this winter.
Russian forces have “been much more clearly setting conditions for an offensive” in the northwestern part of the Luhansk region, the institute said, citing increased transport of Russian military equipment and personnel to the area.
Andrew E. Kramer contributed reporting.