Russian Military Mobilization on Ukraine’s
Borders and in Occupied Crimea
April 27, 2021
In March 2021, Russia began massing troops on the Ukrainian border and in Ukraine’s occupied Crimea
region. Observers have disagreed about whether Russia is preparing for a future invasion or engaging in
coercive signaling. Russia continued to build up its forces in April, dismissing concerns and stating that it
was conducting military exercises. On April 22, Russia announced that most units would return to their
permanent bases but some would remain deployed through upcoming exercises in September. Which
units will remain and which will return to their bases remains to be seen. Congress has expressed support
for Ukraine’s territorial integrity and for deterring Russian aggression.
Russian Troop Deployments
Despite a cease-fire negotiated in July 2020, fighting between Ukrainian armed forces and Russia-led
rebel fighters in the Donbas region of eastern Ukraine has increased since February 2021. Both sides have
reported increased casualties and cease-fire violations, including the use of heavy artillery. International
monitors have reported numerous cease-fire violations, denial of passage along the contact line, and
electronic interference with unmanned aerial vehicles used to monitor the cease-fire.
As tensions increased, Russia began conducting military exercises on Ukraine’s border and in Ukraine’s
occupied Crimea region in March 2021. At the same time, Russia accused Ukraine of preparing an
offensive to retake separatist regions in the Donbas, without offering evidence of such a buildup. Russia
increased its military posture in Crimea, where airborne troops conducted drills, and Russian Defense
Minister Sergei Shoigu announced plans to relocate Russia’s 56
th
Air Assault Brigade to Feodosia,
Crimea. Russia conducted additional exercises on the Ukrainian border, and reports indicated that Russian
troops failed to return to their bases after exercises concluded. This amassing caused significant concern
in Ukraine and among Western governments, with U.S. European Command raising its watch level to
“potential imminent crisis.” In March and April, U.S. Secretary of State Antony Blinken, Secretary of
Defense Lloyd Austin, and Chairman of the Joint Chiefs of Staff General Mark Milley held calls with
their Ukrainian counterparts. President Biden held a call with Ukrainian President Volodymyr Zelensky
on April 2.
