Ukrainian lawmakers passed an army mobilization bill on Thursday, triggering outrage as it omitted provisions for discharging long-serving soldiers.
Meanwhile, Moscow continued its assault on the country's energy infrastructure, targeting a power station in the Kyiv region.
Kyiv has been facing difficulties on the battlefield for months, exacerbated by a lack of U.S. military aid due to congressional blockades, as well as shortages of manpower and ammunition.
Russia further escalated tensions by launching aerial attacks on five Ukrainian regions, resulting in at least four fatalities in the southern city of Mykolaiv.
The strikes also caused extensive damage to a crucial power station near Kyiv, which supplied electricity to Kyiv, Zhytomyr and Cherkasy regions, according to energy officials.
Ukrainian President Volodymyr Zelenskyy urged the West not to "turn a blind eye" to Russia's aerial attacks and to provide more air defenses.
He was speaking during a visit to Lithuania, one of Kyiv's staunchest allies against Russia.
Zelenskyy also signed a 10-year security cooperation agreement with Lithuania's neighbor Latvia, the latest in a number of similar agreements – which are not mutual defense pacts – with NATO countries.
Back at home, the Ukrainian parliament, the Rada, adopted a mobilization bill that was opposed for months by many in a country increasingly exhausted by war.
Facing pressure from army officials, lawmakers had a day earlier scrapped a clause in the bill that would have allowed soldiers fighting for more than 36 months to return home.
Soldiers at the front told Agence France-Presse (AFP) on Wednesday they were in "shock" about the demobilization clause being ditched.
The bill, which needs to be signed into law by Zelenskyy, will strengthen punishments for draft dodgers and sets out new procedures for troop call-ups.
Russia's invasion of Ukraine has dragged on for more than two years, with no end in sight to fighting despite much of the front being virtually frozen.
Zelenskyy said Moscow had fired more than 40 missiles and 40 drones at sites across Ukraine overnight, targeting "critical infrastructure."
In the Kyiv region, officials said a Russian strike destroyed a key power plant.
"Russian troops completely destroyed the Trypilska TPP (power station)," Ukraine's Energy Ministry said.
"All workers who were on shift during the shelling are alive," it added, saying the strike caused a fire.
State company Centrenergo, which operates the plant, said it was the "largest supplier of electricity in Kyiv, Cherkasy, and Zhytomyr regions."
"The scale of destruction is terrible. It can't be calculated in financial terms," Centrenergo Chairperson Andriy Hota said.
Built in the 1960s, the plant became the main generating facility in the area following the shutdown of the Chernobyl nuclear power plant.
It was also a major employer for the city of Ukrainka, south of the capital.
The town's mayor had earlier advised locals to shut their windows while firefighters sought to extinguish the blaze at the plant.
"I ask everyone to close the windows in their homes tightly so as not to breathe in harmful combustion products," Oleksandr Turenko said.
Moscow said it had launched what it called "retaliatory strikes" on Ukraine's energy facilities after a spate of attacks by Kyiv's forces on Russian oil refineries.
Ukraine's southern command said at least four people were killed in an attack on Mykolaiv.
"They insidiously hit Mykolaiv in the middle of the day," it said.
"According to preliminary information, four civilians were killed, five were wounded."
The Ukrainian city of Kharkiv – which is being pounded on an almost daily basis at present – was also attacked again, a day after a strike killed three people there.
Ukrainian Interior Minister Igor Klymenko described a "massive" attack that lasted "for several hours."
In Ukraine's westernmost region of Lviv, authorities said Russian troops attacked a gas distribution facility and an electricity substation.
Russia, meanwhile, said it had destroyed 12 Ukrainian drones overnight, including three as far east as its Mordovia republic, more than 500 kilometers (300 miles) from the border.
Others were destroyed over the Kursk, Tambov, Belgorod, Bryansk and Lipetsk regions, it said.
Both countries have been firing dozens of drones at each other in waves of overnight attacks throughout the year, now in its third year.
In Moscow, the Kremlin criticized plans to hold a Ukrainian peace conference in Switzerland in June.
"We said many times that the process of (peace) talks without Russia makes no sense," Kremlin spokesperson Dmitry Peskov told reporters.
