US Secretary of State Antony Blinken will try to defuse a crisis with Moscow over Ukraine when he meets with Russian Foreign Minister Sergei Lavrov in Geneva on Friday.
Blinken's talks in the Swiss city follow a frenzied round of shuttle diplomacy in Europe as fears mount over Russia's build-up of forces along Ukraine's borders.
He was already in Kiev and Berlin this week.
While the US and its Western allies are demanding a pull-back of the Russian troops, Moscow is demanding certain security guarantees and an end to the eastward expansion of the NATO military alliance.
Russia further objects to US military assistance to Ukraine, where a conflict has simmered in the east between Russian-backed separatists and Ukrainian forces since 2014.
"All we're trying to do is to make sure to the best of our ability that ... Ukraine has the means to defend itself and that might perhaps deter further aggression by Russia," Blinken said Thursday.
Efforts to ease the threat of large-scale Russian military operations against Ukraine have been in full swing for the past few weeks - including at NATO, the Organization for Security and Cooperation in Europe and direct talks with Moscow - but have so far produced no tangible results.