Russia had suspicions that Ukraine planned to attack Russia during the Navy Day parade which was attended by President Vladimir Putin last month and Moscow contacted Washington about its concerns, Russian state television reported.
Russian television said that the details were a state secret and provided no further details. Ukraine's foreign ministry did not immediately respond to a request for comment on the report.
The report cited Deputy Foreign Minister Sergei Ryabkov as saying that the concerns were so great about the suspected attack that Defence Minster Andrei Belousov contacted U.S. Defense Secretary Lloyd Austin about the suspicions.
Reuters was unable to immediately verify the report.
The New York Times reported that Austin had taken a call from Belousov on July 12 about a covert Ukrainian operation planned against Russia that Moscow believed had the blessing of the United States.
The Times cited two unidentified U.S. officials as saying that Pentagon officials were surprised by the Russian allegation and unaware of any such plot.
Still, the Russian concerns were taken seriously enough for Washington to contact Ukraine and caution Kyiv that if it was planning such an operation then it should not carry it out.
