Russia Launches Fresh Missile Strikes, Widening Attacks on Ukrainian Power Plants

“Ukraine is under fire by the occupiers. They continue to do what they do best—terrorize and kill civilians,” Mr. Zelensky said on his Telegram channel.

The deputy head of Mr. Zelensky’s administration, Kyrylo Tymoshenko told Ukrainians to prepare for blackouts across the country after days of Russian strikes.

“The situation is critical,” he said in a television interview.

The Kremlin’s strategy of targeting critical infrastructure is intended to sow panic in the population while diminishing the country’s resolve—and ability—to fight. Tuesday’s strikes hit targets in Zhytomyr, Kharkiv and Dnipro, cutting the supply of electricity and water. Other Russian strikes in the southern region of Mykolaiv overnight used modified S-300 surface-to-air missiles to hit residential houses, killing at least one person and leveling parts of the city’s flower market.

Russian air attacks in recent weeks have underscored Ukrainian officials’ calls for more air-defense capabilities from the West. On Monday, a swarm of Iranian-produced drones struck central Kyiv, hitting energy infrastructure and at least one residential block.

On Tuesday, a U.S. senior military official said the Biden administration was working to get the first deliveries of the National Advanced Surface-to-Air Missile System, or NASAMS, a short and medium-distance system, to Ukraine in the coming weeks. European countries are also contributing various air-defense systems.

“From a U.S. standpoint, we’re going to continue to stand by the Ukrainians and provide them with the support that they need, as they try to push these Russian forces back,” the official said.

The U.S. has so far spent nearly $20 billion in security assistance for training and equipment for Ukraine since 2014, when a street protest movement ousted a Moscow-back president in favor of a pro-Western government. Moscow, which called the ouster a coup, then aided armed separatists in Ukraine’s primarily Russian-speaking east, starting the conflict between Kyiv and the Kremlin.

Washington’s assistance has provoked Russian officials to warn that their real enemy isn’t Ukraine but the U.S. It has also prompted the U.S. to modify optics around military exercises. A wargame planned to exercise the North Atlantic Treaty Organization nuclear deterrence capabilities started early this week in Belgium, involving fourth and fifth-generation jet fighters and B-52 long-range bombers. A NATO statement said the exercises had been long planned and weren’t linked to any current events.

Russian Deputy Foreign Minister Sergei Ryabkov said Moscow would be closely watching the exercises to understand NATO’s stance toward nuclear deterrence.

“Undoubtedly, we are carefully monitoring this,” he said.

Russian President Vladimir Putin’s nuclear saber-rattling has unnerved observers, though many still see it as little more than rhetoric. The U.S. has said it hasn’t seen any indications that Russia has changed its nuclear stance.

Russian occupation of Europe’s biggest nuclear-power plant in Ukraine’s Zaporizhzhia region however has also raised fears over Moscow’s ability to maintain the integrity of the system while pressuring Ukrainian experts at the power plant to pledge loyalty to the Kremlin.

Energoatom said Tuesday that two more managers of the power plant were abducted on Monday.

“Currently, nothing is known about their whereabouts and state,” the Ukrainian state nuclear company said.

Tuesday’s strikes also came hours after a Russian Su-34 jet fighter crashed into a housing complex in the Russian city of Yeisk, near Crimea, killing 13 residents, injuring nearly two dozen people and forcing more than 500 to temporarily leave their homes, Russian news agency Tass said.

Russian investigators said a technical malfunction likely caused the war plane, which was flying nearby, to crash into the nine-storey apartment complex, reducing parts of it to rubble and sending flames throughout much of the rest of the building.

Demining teams were working through the rubble on Tuesday to ensure none of the plane’s munitions posed a danger to repair efforts.

—Matthew Luxmoore contributed to this article.

Write to Thomas Grove at thomas.grove@wsj.com