Obama insisted that Russia and separatist forces in Ukraine had to grant full access to the conflict zone for a special monitoring mission from the Organization for Security and Cooperation in Europe.
The Minsk agreement was reached among Russia, Ukraine and European powers in February 2015 and called for an OSCE-observed ceasefire in eastern Ukraine.
However, few of its commitments have been met and skirmishes continue between pro-Russian rebels and government forces in Ukraine’s eastern regions of Luhansk and Donetsk.
More than 9,000 people have been killed and some 20,000 injured since the uprising against Ukraine’s pro-Western leadership erupted in April 2014, according to the United Nations.
Kiev and the West accuse Russia of supporting the insurgents and sending regular troops across the border. Moscow, which has been subject to sanctions by the European Union and the US, has denied the claims.