The United States and its allies will respond in a united and decisive way to "an unprovoked and unjustified attack by Russian military forces" on Ukraine, US President Joe Biden said after blasts were heard in the Ukrainian capital of Kyiv.
"President (Vladimir) Putin has chosen a premeditated war that will bring a catastrophic loss of life and human suffering," Biden said in a statement.
"Russia alone is responsible for the death and destruction this attack will bring. The world will hold Russia accountable."
Biden said he would announce on Thursday further consequences to be imposed on Russia by the United States and its allies.
