Kerry said all parties should make efforts to fully implement the Minsk agreement on halting the conflict in the Donbas, and said he hoped that one day Ukraine would be able to become a "bridge" between the West and Russia.

In turn, Steinmeier has stressed the "explosive potential" that the Ukrainian conflict still harbors, warning that this threatens the peace of Europe.

"We have to influence the situation in a way that ensures the unity of Ukraine," said Steinmeier.

Finally, it is necessary to ensure there is proper control of the Ukrainian-Russian border, and to achieve the withdrawal of troops from the buffer zone between two states, he said.