US President Donald Trump announced to impose new sanctions on Russia within 10 days if Moscow does not end its more than three-year war in Ukraine.
Earlier President Trump set 50-day deadline has now shorted it to 10 to 12 days.
But, speaking to reporters, Trump said he had not yet received a response from Russia.
The move appears to be a new step by the US to pressure Moscow, as the ongoing conflict in Ukraine has caused heavy casualties and heightened international tensions.