RomaniaÂ is calling for a permanent NATO fleet in the Black Sea to deter Russian aggression. Bucharest says it will begin negotiating with NATO on the matter this month, Balkan Insight reports. The fleet may include ships from Black Sea NATO states Bulgaria, Romania and Turkey. Under the 1936 Montreux Convention, only Black Sea states can have warships stationed in the sea for more than 21 days at a time. Other NATO states like the U.S., Germany and Italy could rotate ships in and out.