In remarks to reporters released by his office on Saturday, Zelenskiy said Washington had proposed a new round of talks between Kyiv and Moscow to take place in Miami in a week and that Kyiv had agreed to the proposal.
"The Americans are proposing that the parties end the war before the start of this (northern) summer, and will likely pressure the parties to adhere to this schedule," Zelenskiy said.
"The (mid-term Congressional) elections are definitely more important to them. Let's not be naive. And they say they want to get everything done by June."
Zelenskiy's statement confirmed an earlier Reuters report on the proposed timing for a deal. Ukraine had suggested a sequencing plan, Zelenskiy said, but provided no specific details.
Ukraine and Russia concluded two days of US-brokered peace talks in Abu Dhabi this week without a major breakthrough but the two sides agreed to exchange 157 prisoners of war each, resuming such swaps after a five-month pause. Zelenskiy said that the POW swap would continue.
The military teams discussed in detail technical aspects on how to monitor a potential ceasefire, Zelenskiy said.
Security guarantees for Ukraine and agreements on economic cooperation, referred to by officials as "the prosperity plan" that outlined Ukraine's postwar recovery, were also discussed.
Zelenskiy said he had reports from his intelligence services on discussions in which Russia's special envoy Kirill Dmitriev proposed co-operation deals between Russia and the United States worth as much as $US12 trillion.
He said that any such bilateral agreements between Russia and the United States could not violate the Ukrainian constitution.
The deadline news follows a massive Russian air attack on Ukrainian energy facilities, targeting electricity generation and distribution.
Zelenskiy said the overnight attack involved more than 400 drones and some 40 missiles of various types, targeting the grid, generation facilities and distribution substations.
Nearly four years into the war that began with Russia's full-scale invasion of its neighbour, Ukraine's battered energy sector is crumbling under the Russian strikes, accumulated wartime damage and bitterly cold winter weather.
"Every day, Russia could choose real diplomacy, but it chooses new strikes," Zelenskiy posted on X.
"It is crucial that everyone who supports the trilateral negotiations respond to this. Moscow must be deprived of the ability to use the cold as leverage against Ukraine."
Moscow did not immediately comment on the attacks.
Energy Minister Denys Shmyhal said the strikes hit two thermal power stations in Ukraine's western regions and core elements of the Ukrainian electricity distribution system - substations and key electricity distribution lines.
"Russian criminals carried out another massive attack on Ukraine's energy facilities," Shmyhal said on the Telegram app. "Energy workers are ready to start repair works as soon as the security situation allows."
The strikes were launched as temperatures began to drop and are forecast to fall to minus 14C in the coming days.
The new Russian attacks on the energy system also come just days after the latest round of the US-brokered talks between Ukraine and Russia on how to end the war.
Despite pressure from US President Donald Trump's administration and rounds of talks, diplomatic efforts have so far brought no tangible results.
Since 2025, Moscow has intensified its attacks on the Ukrainian power grid and other energy infrastructure, forcing frequent blackouts across Ukraine and plunging millions into darkness for hours.
Ukrainian officials said emergency power cuts were introduced across the nation. Shmyhal said the government asked Poland for emergency power imports to help the Ukrainian grid.
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