Ukrainian President Volodymyr Zelensky has said that he had a long and "substantive" phone call with US President Donald Trump's special envoy Steve Witkoff and Mr Trump's son-in-law Jared Kushner.
"Ukraine is determined to keep working in good faith with the American side to genuinely achieve peace. We agreed on the next steps and formats for talks with the United States," Mr Zelensky said on X.
Mr Witkoff and Mr Kushner had held two days of talks with Ukraine's senior negotiator Rustem Umerov in Miami this week, which both sides called "constructive discussions on advancing a credible pathway toward a durable and just peace in Ukraine".
Mr Witkoff had been expected to brief Mr Umerov on his meeting in Moscow this week with Russian President Vladimir Putin.
Mr Zelensky said he was waiting for Mr Umerov to give him a detailed report in person in Kyiv.
"Not everything can be discussed over the phone, so we need to work closely with our teams on ideas and proposals," Mr Zelensky said.
"Our approach is that everything must be workable - every crucial measure for peace, security, and reconstruction."
Ukrainian negotiators were to meet in Florida with Mr Witkoff for a third straight day of talks on the US-drafted plan on how to end the almost four-year war.
The call comes after Russian drone and missile strikes on Ukraine targeted critical infrastructure, including energy sites and railways, triggering heating and water outages for thousands of households.
Russia launched 653 drones and 51 missiles at Ukraine, Kyiv's air force said.
"The main targets of these strikes, once again, were energy facilities," Mr Zelensky said on social media.
"Russia's aim is to inflict suffering on millions of Ukrainians," he said.
The drones and missiles had also targeted energy facilities in the Chernigiv, Zaporizhzhia, Lviv, and Dnipropetrovsk regions, Kyiv officials said.
In the Odesa region, "9,500 subscribers remain without heat supply and 34,000 subscribers remain without water supply due to damage," Restoration Minister Oleksiy Kuleba said.
A Russian drone strike also hit and "burned down the main railway station building in Fastiv," a city around 70 kilometres southwest of Kyiv, Mr Zelensky said.
There were no casualties, but "suburban train traffic has been disrupted," Ukraine's state rail operator Ukrzaliznytsya added.
An emergency coordination meeting of Ukrainian ministers was convened in the wake of the strikes, Prime Minister Yulia Svyrydenko said on X.
Additional "rolling power outages will be required across the country" to stabilise the system while repairs continued, she added.
Neighbouring Moldova's national energy provider said it was also affected by the strikes.
"Following attacks on Ukraine's energy system... an important energy group has been disconnected and the interconnection lines are close to their limit," Moldelectrica said on social media.
It said it had "requested emergency assistance from Romania as a preventive measure for the next few hours," and urged citizens to "consume electricity rationally".
Despite the US-led push to end the conflict, Russia has routinely targeted Ukraine's power and heating grid, destroying a large part of the key civilian infrastructure.
As with previous waves of attacks, the Russian defence ministry said its strikes had targeted "Ukrainian military-industrial complex enterprises and the energy facilities that support them," and added that "all designated targets were hit".
Witkoff holds 'productive' talks with Umerov, US officials say
US President Donald Trump's special envoy Steve Witkoff held productive talks with Ukraine's senior negotiator Rustem Umerov in Miami over the past two days, US officials said, with further talks scheduled.
Mr Witkoff and the president's son-in-law Jared Kushner met Mr Umerov and General Andriy Hnatov, Ukraine's military chief of general staff, for what both sides called "constructive discussions on advancing a credible pathway toward a durable and just peace in Ukraine."
At yesterday's meeting, the group's sixth of the past two weeks, Mr Umerov underscored that Ukraine's priority is to secure settlement that protects its independence and sovereignty, ensures the safety of Ukrainians, and provides a stable foundation for a prosperous democratic future, the State Department and Mr Umerov said in a joint statement.
The participants discussed the results of Mr Witkoff and Mr Kushner's meeting with Russian President Vladimir Putin in Moscow this week, and steps that would help end the war, it said.
Marathon talks in Russia on Tuesday did not produce a compromise on a possible peace deal to end the war in Ukraine, potentially aggravating Mr Trump's growing impatience with both Ukraine and Russia over the war.
Mr Trump has repeatedly complained that ending Europe's deadliest conflict since World War II has been one of the elusive foreign policy aims of his presidency.
The US president has at times scolded both Mr Putin and Mr Zelensky.
During this week's talks, US and Ukrainian officials also agreed on "the framework of security arrangements and discussed necessary deterrence capabilities to sustain a lasting peace," the State Department said, without spelling out details.
The two parties said real progress toward any agreement, however, would depend on Russia's readiness to show a serious commitment to long-term peace, including steps toward de-escalation and an end to killings, it added.
In addition, they discussed Ukraine's post-war reconstruction, joint US-Ukraine economic initiatives, and long-term recovery projects, the State Department said.
A White House official earlier said the meetings, which are taking place at an undisclosed location in Miami, were productive, adding: "Progress was made."
Mr Witkoff and Mr Kushner had agreed before their meeting with Mr Putin that they would brief their Ukrainian counterparts afterwards, a source familiar with the matter said.
Yuri Ushakov, the Kremlin's top foreign policy adviser, said that Mr Putin and Mr Witkoff had achieved a level of understanding that made their discussions "truly friendly."
Mr Putin met Mr Witkoff and Mr Kushner for five hours in the Kremlin and focused on a US-backed plan for a settlement of the war in Ukraine, where Russia launched a full-scale invasion in 2022.
Mr Putin later described the talks as "very useful".
