Ukrainian President Petro Poroshenko has submitted a draft bill to parliament which seeks to terminate a friendship treaty with Russia.
Tensions have flared between Kiev and Moscow over Russia's seizure of three Ukrainian naval ships and their crews last month.
Kiev says it wants to terminate the treaty due to what it calls Russian aggression.
The treaty was ratified in 1998 and automatically renews every decade unless one side advises the other of its intention to end the agreement.