I understand the Israeli need to intercept this flotilla. They need to save face. Of course, the flotilla could be inspected at their last port of call, and monitored all the way to Gazan waters. There is great technology to make sure nothing is added to the ships. The main issue here is that Israel must have total control, but hopefully when they stop it--and they will, they will not do it in international waters like the last time.
Suspected assailant in car-ramming attack in West Bank shot (Haaretz)
from the article: Israel prepping to block next Gaza flotilla