Russian President Vladimir Putin put more than 65,000 troops on combat alert on Saturday and ordered them to participate in a drill, according to multiple reports.
The military exercise is the largest since Russia annexed the Crimean peninsula from Ukraine in March, Bloomberg News reports, and came after Ukraine called a weeklong ceasefire to decrease violence in the country’s eastern region.
On Friday, the Obama administration also announced it was imposing new sanctions that would freeze the assets of seven Ukrainian separatists.
A senior administration official said Secretary of State John Kerry and the White House are calling members of the European Union to attract support for additional penalties.
The U.S. has said it believes Russia sent tanks and rocket launchers to its border with Ukraine last week, and there are more tanks, fuel trucks and support vehicles on the way.
Putin ultimately said Saturday he supports Ukrainian President Pyotr Poroshenko’s decision to order a ceasefire and is open to conducting peace talks with all parties.
Putin “urges all warring parties to stop all hostilities and begin talks”, the presidential press service said. Putin, however, said he believes that Poroshenko’s peace plan “will not be viable and realistic without practical steps towards negotiations.”
This story was updated at 7:00 p.m.