There are two distinct issues in the Gaza situation, one is the "siege" and the other is the Naval blockade. 1. The "siege" is the prevention of delivery to Gaza of raw material and items beyond basic necessities of life, and prevention of exports. This destroys the Gaza economy and reduces Gazans to destitution. The siege operates over land, sea, and air and was started when Hamas took over the Gaza government. 2. The naval blockade prevents ships from going in or out of Gaza and was in effect even before Israel left Gaza. Its role is the prevention of weapon smuggling. Imports were in the past handled through the port of Ashdod, which enabled Israel to examine them. The international community is of course against the "siege", but was not against the naval blockade. The activists tried to break the "siege", but since they couldn't do it over land, they picked the naval part.
Two Turkish soldiers, five Kurdish militants killed in attack (Reuters)
from the article: Israel adds Turkish organizers of Gaza flotilla to terror watch list