US Secretary of State Antony Blinken arrived in Ukraine on Wednesday amid mounting fears that a Russian invasion of Ukraine could be imminent.
Mr Blinken was due to hold discussions with President Volodymyr Zelensky in Kyiv, before meeting European allies in Berlin and his Russian counterpart in Geneva on Friday.
Russia has repeatedly denied planning to invade neighbouring Ukraine. But senior US officials say Moscow could attack at "any point".
An estimated 100,000 Russian
troops have been deployed near Ukraine's borders and White House Press Secretary Jen Psaki told reporters on Tuesday the build-up had created extremely dangerous situation.
Senior state department officials have indicated that Russian Foreign Minister Sergei Lavrov may be offered the option of a diplomatic off-ramp in Geneva. Ms Psaki said no option was off the table and that Mr Blinken would highlight very clearly there is a diplomatic path forward.