Russian President Vladimir Putin showed off what he said is an indefensible nuclear missile with a video showing warheads raining down on what appears to be Florida.
Putin said his country would respond instantly to "any use of nuclear weapons" against Russia or its allies.
U.S. officials responded to the display. White House press secretary Sarah Sanders said Putin's claims were clear evidence Russia was violating treaties by "developing destabilizing weapons systems."
State Department spokeswoman Heather Nauert said it was "unfortunate" to see a video depicting "a nuclear attack on the United States." She said Putin was speaking to a single person: President Donald Trump.