Secretary of State Antony Blinken spoke with French Foreign Minister Jean-Yves Le Drian late Sunday about "concerning" Russian military activity "in and around Ukraine."
The two senior diplomats discussed "reports of Russian military activity in and around Ukraine and their unwavering commitment to Ukraine's sovereignty and territorial integrity," according to State Department spokesman Ned Price.
On Saturday, Blinken and Le Drian met and discussed "coordinated efforts to address Iran's nuclear program," Price added.
Western allies have expressed growing concern over recent Russian force maneuvers near the country's Ukrainian border.
The Ukrainian army has been embroiled in a simmering battle with rebels backed by the Kremlin in the Donetsk and Lugansk areas since 2014 when Russia grabbed the Crimean peninsula.
Kyiv said Friday that an explosive device murdered two Ukrainian soldiers in the country's separatist east. At the same time, recent social media images show Russia massing troops, tanks, and missiles near the Ukrainian border.
Following an increase in violence at the start of the year, Russia gathered over 100,000 troops on Ukraine's borders in the spring, increasing worries of a significant escalation of the conflict.
Russia later declared a retreat, although Ukraine and its partner, the United States, both stated at the time that the drawdown would be limited.
Over 13,000 people have been killed in the fighting.
Ukraine and its Western allies accuse Russia of crossing the border with troops and armaments. Moscow has vehemently refuted those allegations.