Russian missile strikes across Ukraine on Monday had “widespread impact” on the country’s power grid, sparking concerns in the West, according to Pentagon officials. 

“Ukraine has been able to defend against some of these attacks, but damage to the electric grid and water supply are serious concerns directly harming the civilian population,” a senior U.S. defense official told reporters. 

Russian missiles rained down on several Ukrainian cities early Monday, leaving about 80 percent of Kyiv without water and other large swaths of the population without electricity, according to the city’s mayor.  

The missile barrage, which took place at about 7 a.m. local time, targeted “military and civilian infrastructure facilities with 55 aircraft guided missiles, 45 of which were shot down by our defenders,” the Ukrainian military’s General Staff later claimed. 

And Ukrainian Prime Minister Denys Shmyhal said 18 targets were hit in 10 regions, according to The Washington Post

Another U.S. military official said they did not have specific information to provide as far as the extent of the damage but were “keeping a close eye” on it and still gathering information.   

“In terms of the infrastructure, by virtue of the electrical grid being impacted, we are seeing impacts in terms of water supply systems, water treatment, things like that, which is affecting access to water among the civilian population,” they said.  

The Russian strikes mark the most widespread missile barrage since a similar campaign earlier this month when Moscow, over several days, pummeled Ukraine’s infrastructure and power grid. Ukrainian and Western officials have expressed concern over the country’s energy output as winter looms, with fears that a humanitarian crisis will soon be at hand as the days grow colder.  

The most recent Kremlin strikes are in retaliation for what Moscow claims are weekend drone attacks that targeted Russian warships in the Crimean Peninsula, though Ukraine has not claimed responsibility for the attack.  

The U.S. military official said the Biden administration is “tracking reports of an alleged attack against Russian navy vessels in Sevastopol,” a city on the Black Sea in the annexed territory of Crimea. They also confirmed there “were explosions there” but would not say what caused the explosions and did not have a damage assessment to share.