US Secretary of State Antony Blinken and Russian Foreign Minister Sergei Lavrov are meeting for talks in Geneva amid mounting fears that Russia could be about to invade Ukraine.
On Thursday Mr Blinken warned Moscow of grave consequences if any of its forces crossed the border.
Russia has 100,000 troops at the border, but denies planning to invade.
President Vladimir Putin has issued demands to the West, including that Ukraine be stopped from joining Nato.
He wants the Western defensive alliance to abandon military exercises and stop sending weapons to eastern Europe, which Moscow sees as its backyard.
Russia previously seized and annexed the Crimean peninsula in southern Ukraine in 2014. Ever since, Ukraine's military has been locked in a war with Russian-backed rebels in areas near the border. The conflict has claimed 14,000 lives and caused at least two million people to flee their homes.