Russia has fired missiles at targets across Ukraine, from Kharkiv in the north to Odessa in the south and Zhytomyr in the west.
Buildings and infrastructure were affected in Kharkiv and Odessa, with power cuts in many areas. There are also reports of attacks on the capital city of Kiev.
The attacks come at a time when ground fighting for the city of Bakhmut in eastern Ukraine continues.
A US intelligence chief has suggested the war could last for years.
Russian President Vladimir Putin launched his offensive just over a year ago. Since then, tens of thousands of fighters and civilians have been killed or injured, and millions of Ukrainians have become refugees.
Emergency services in Kiev are at the scene of explosions in the western and southern districts of the capital, where Mayor Vitaliy Klitschko said the blasts took place.
Mr Klitschko said cars were burning in the courtyard of a residential building and urged people to stay in shelters.
Its governor, Maxim Marchenko, said a major missile attack hit an energy facility in the port city of Odessa, knocking out power. He added that residential areas were also affected but there was no loss of life.
“About 15” attacks hit Kharkiv city and region, including “key infrastructure facilities” and a residential building, regional administration chief Oleg Senigobov said.
Other areas affected include Venetia and Rivne in the west and Dnipro and Poltava in the center.
US Director of National Intelligence, Avril Haynes, suggested on Wednesday that President Putin may be planning to end the years-long war, but that Russia is not strong enough to launch a major new offensive this year.
He said the war in Ukraine had become a “grinding war” in which neither side had a definite military advantage.
“We don’t foresee a Russian military recovery this year that would allow for major territorial gains, but Putin likely calculates the timing to work in his favor, including a possible pause in the fighting. Prolonging the war may be their best option. To secure Russia’s strategic interests in Ukraine, even if it takes years.”
Ms Haynes said Russia could turn to defending areas it now holds, adding that it needed additional “mobilisation and third-party shells” to maintain its level of operations in Ukraine. Ammunition sources” will be required.
Ukraine’s military says it has repelled heavy Russian attacks on the eastern city of Bakhmut, despite Russian forces taking control of its eastern half.
Moscow has been trying to take over Bakhmut for months, as both sides have suffered heavy losses in a grinding war of withdrawal.
The General Staff of the Armed Forces of Ukraine said that “the enemy has continued its attacks and has shown no let-up in attacking the city of Bakhmut.” “Our defenders repelled attacks on Bakhmut and surrounding communities.”
Western officials say between 20,000 and 30,000 Russian troops have been killed or wounded in the battle for the Ukrainian city of Bakhmut since last summer. The data cannot be independently verified.
