Barack Obama said sanctions against Russia must be tightened until Moscow makes move to de-escalate situation in Ukraine, Interfax-Ukriane reported.

The imposed sanctions are really effective, and it is important to introduce further restrictions against Russia, Obama said during a joint press conference with Estonian counterpart Toomas Ilves.

Obama said the U.S. prefers to see powerful, productive and cooperating Russia.

Earlier European Commission made recommendations to EU ambassadors regarding additional restrictions against Russia.