The United States believes that Russian President Vladimir Putin's threatened retaliation against Ukraine over its drone attack last weekend has not happened yet in earnest and is likely to be a significant,

A large Russian drone-and-missile attack targeted Ukraine's eastern city of Kharkiv on Saturday, killing at least three people and injuring 21, local officials said. The barrage — the latest in near daily widescale attacks — included aerial glide bombs that have become part of a fierce Russian onslaught in the three-year war.