KYIV - Ukrainian President Volodymyr Zelensky said that the United States is seeking to end the Russia-Ukraine conflict by June, the Ukrinform news agency reported Saturday.

"The Americans are proposing that the parties end the war by the beginning of this summer, and they will likely exert pressure on the parties in line with this timetable," Zelensky told reporters.

He suggested that the proposal deadline is linked to the start of the US Congress election campaign.

Currently, there are four documents that will form the basis of security guarantees for Ukraine after the end of the hostilities, Zelensky said.

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He said the documents include a security guarantees agreement between Ukraine and the United States, an agreement on the creation of the Coalition of the Willing, a document on prospects for Ukraine's membership in the European Union, and a short framework document that links the other three.

Meanwhile, Russian forces attacked Ukraine's energy infrastructure overnight on Saturday, for the second time in less than a week, Ukraine's Energy Minister Denys Shmyhal said.

The strikes targeted the Burshtyn and Dobrotvir thermal power plants in western Ukraine, as well as substations and overhead transmission lines, the minister said.

He further said personnel unloaded units at nuclear power plants as a precautionary measure.

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Ukraine's state-run energy company Ukrenergo has requested emergency assistance from Poland in the wake of the attack, Shmyhal added, while the company said it has imposed emergency power outages across most of the country.

The previous attack on Ukraine's energy facilities was carried out on Tuesday.