Russia has noted a significant increase in activity by U.S. bombers near its eastern borders, the RIA news agency quoted Defence Minister Sergei Shoigu as saying on Tuesday.
The accusation comes days after President Vladimir Putin said the West was taking Russia's warnings not to cross its "red lines" too lightly and told foreign ministry officials that Russia needed to seek long-term guarantees of its security from the West.
(Reporting by Polina Devitt; Writing by Gabrielle Tétrault-Farber; Editing by Kevin Liffey)
