Ukraine vowed to strengthen its armed forces after Russia launched its biggest aerial assaults on cities since the beginning of the war, forcing thousands to flee to bomb shelters and prompting Kyiv to halt electricity exports to Europe.
Missiles hit targets across Ukraine on Monday morning, killing 14 people and injuring scores, as they tore into intersections, parks and tourist sites.
Explosions were reported in Kyiv, Lviv, Ternopil and Zhytomyr in western Ukraine, Dnipro and Kremenchuk in the centre, Zaporizhzhia in the south and Kharkiv in the east, Ukrainian officials said.
The barrage of dozens of cruise missiles fired from air, land and sea was the most widespread wave of air strikes to hit away from the front line, at least since the initial volleys on the war's first day, Feb. 24.
Russian President Vladimir Putin said he ordered "massive" long-range strikes after accusing Ukraine of an attack on a bridge linking Russia to annexed Crimea on Saturday, but the United States said the scale of the attacks meant they had likely been planned for longer.
Ukrainian President Volodymyr Zelenskiy spoke to U.S. President Joe Biden on Monday and wrote on Telegram afterwards that air defence was the "number 1 priority in our defence cooperation."
"We will do everything to strengthen our armed forces," he said in a Monday night address. "We will make the battlefield more painful for the enemy."
Biden told Zelenskiy the United States will provide advanced air defence systems. The Pentagon said on Sept. 27 it would start delivering the National Advanced Surface-to-Air Missile System over the next two months or so.
A total of 14 people were killed and 97 were injured, the State Emergency Service of Ukraine reported. The rush-hour attacks were deliberately timed to kill people and knock out Ukraine's power grid, according to Zelenskiy.
Prime Minister Denys Shmyhal reported 11 major infrastructure targets were hit in eight regions, leaving parts of Ukraine with no electricity, water or heat. He promised to restore utilities as quickly as possible.
As it tried to end blackouts, Ukraine halted electricity exports to the European Union, at a time when the continent already faces surging power prices that have stoked inflation, hampered industrial activity and caused sky-high consumer bills.
The Kremlin's air strikes come three days after a blast damaged the bridge it built after seizing Crimea in 2014. Russia blamed Ukraine and called the deadly explosion "terrorism".
"To leave such acts without a response is simply impossible," said Putin, alleging other, unspecified attacks on Russian energy infrastructure. He threatened more strikes in future if Ukraine hits Russian territory.
The United States, however, said attacks of such a scale could not have been put together in just a couple of days.
"It likely was something that they had been planning for quite some time," White House national security spokesperson John Kirby told CNN. "That's not to say that the explosion on the Crimea bridge might have accelerated some of their planning."
Ukraine, which views the bridge as a military target sustaining Russia's war effort, celebrated the blast without claiming responsibility.
After weeks of setbacks on the battlefield, Russian authorities are facing the first sustained domestic criticism of the war, with commentators on state television demanding ever tougher measures.
Putin responded to Ukrainian advances by ordering a mobilisation of hundreds of thousands of reservists, proclaiming the annexation of occupied territory and threatening to use nuclear weapons.
On Saturday, Russia made its third senior military appointment in the space of a week by appointing Air Force General Sergei Surovikin as commander of Russian forces in Ukraine. He previously commanded Russia's brutal air campaign in Syria.
Russia says it is waging a "special military operation" in Ukraine to rid it of nationalists and protect Russian-speaking communities. Ukraine and the West say it is an unprovoked war of aggression.
Monday's blasts tore a huge crater next to a children's playground in one of central Kyiv's busiest parks. The remains of an apparent missile were buried, smoking in the mud. More volleys struck the capital again later in the morning.
Ukraine's defence ministry said in its evening update Russia had staged at least 84 missile and air strikes, and Ukraine's air defences had destroyed 43 cruise missiles and 13 drones.
Russia's defence ministry said it had hit all its intended targets. Reuters could not independently verify battlefield accounts.
Russia also suffered a setback on the diplomatic front, with the UN General Assembly voting to reject Moscow's call for the 193-member body to hold a secret ballot later this week on whether to condemn its annexations four partially occupied regions in Ukraine.
The General Assembly decided, with 107 votes in favor, that it would hold a public vote - not a secret ballot.
The president of the United Arab Emirates, a member of the group of oil producers known as OPEC+ that rebuffed the United States last week by announcing steep cuts last week, will travel to Russia on Tuesday to meet Putin and push for "military de-escalation", UAE state news agency WAM reported.
Biden and Group of Seven leaders will hold a virtual meeting on Tuesday to discuss their commitment to support Ukraine, the White House said.