John Kerry
John KerryReuters

U.S. Secretary of State John Kerry on Thursday threatened Russia with more sanctions if it continues to stoke unrest in Ukraine, CNBC reported.

"It will not just be a grave mistake, it will be an expensive mistake," Kerry said. He accused Russia of acting deceitfully and purposefully destabilizing the region.

"Nobody should doubt Russia's hand in this," he said, according to CNBC.

"Let's get real. The Geneva agreement is not open to interpretation," added Kerry, noting that "Only one side is keeping its word."

Kerry's comments come one week after global leaders met in Geneva and agreed to de-escalate the situation in Ukraine.

"Ukraine is taking concrete steps to move past" the recent weeks of unrest, Kerry said, noting that no Russian officials have publicly pushed for upholding the Geneva terms of diplomatic resolution. They have, instead, steadily stoked unrest, he stressed.

The United States and the EU have already responded to Russia’s actions in Ukraine by imposing personal sanctions against Russian and Crimean officials involved in the seizure of the peninsula.

Russian President Vladimir Putin, however, has remained unfazed by EU and U.S. economic sanctions, and has responded by drafting his own sanctions on top American senators.