“The Vice President and President Komorowski agreed that Russia and Russia-backed separatists had to fulfill all of the obligations under the Minsk agreements,” the release said.
The obligations include unfettered access for OSCE monitors, the withdrawal of Russian troops and equipment from Ukrainian territory, and return to Ukrainian control of the international border by the end of the year, the release added.
Biden and Komorowski agreed that any further escalation of the conflict by Russia “would be met by increasing costs.”
The main points of the Minsk deal include the implementation of a ceasefire by both sides, in force from February 15, and a heavy weapons pullout within two weeks.
Independence supporters claim they completed the weapons withdrawal on Sunday, thus meeting the deadline imposed by the Minsk deal.
Earlier on Saturday, Ukrainian military spokesman Andriy Lysenko said that Kiev forces are continuing the third stage in the pullout of heavy arms.
Kiev launched a military offensive against independence supporters in the eastern Ukraine regions of Donetsk and Luhansk last April. The confrontation has claimed more than 6,000 civilian casualties, according to the UN.