Russians Have Already Started Hybrid War, Ukraine Says

KYIV, Ukraine—U.S. officials are warning that Russia could be about to attack Ukraine. For many citizens in this embattled country, the assault has already begun.

Ukrainian officials say that Russia, which has positioned more than 100,000 troops around three sides of Ukraine, is stepping up a destabilization campaign involving cyberattacks, economic disruption and a new tactic: hundreds of fake bomb threats.