Is a blockade of a port an act of war?

[Duckhunter935]

14. no, this

Russia has deliberately sunk three of its own ships to block Ukrainian navy vessels into a lake off the Black Sea, officers say, highlighting Moscow’s determination to wear down the morale of Kiev’s forces in Crimea.The Ochakov — a Soviet-era warship decommissioned in 2011 and set to be sold for scrap — was towed to the entrance to Lake Donuzlav on Crimea’s western coast from the Russian base at Sevastopol on Thursday and blown up.

It capsized and, along with two smaller Russian vessels, is now blocking the narrow gap between two spits of land, its hull beaten by rough Black Sea waves.
http://cmsimg.defensenews.com/apps/pbcsi.dll/bilde?Site=M5&Date=20140309&Category=DEFREG01&ArtNo=303090010&Ref=AR&MaxW=640&Border=0&Blocked-By-Sunken-Russian-Ships-Ukraine-s-Navy-Stays-Defiant