What gives Israel's government the right to send commandos the right to board a ship

[Lordpercywoosterxxviii]

no, when a terrorist group declares it intention to break the law , the country to be attacked can defend itself

 

[dstr]

out side of its territory? The boarding of the ships took place more than 70 nautical miles outside Israeli territorial waters, according to IHH.

Accounts say as the helicopter was lowering the commandos they opened fire on the unarmed humanitarian relief workers.

Since this happend in international waters, doesn't it mean it was murder?
The boats left European ports in a consolidated protest organized by two pro-Palestinian groups to deliver tons of food and other aid to Gaza to break a blockade imposed by Israel in 2007.