There is no “legal” anything involved. International “law” is only the collection of various agreements between individual countries that may be “enforced” by the most powerful countries at their whim. The sinking of the Cheonan was not “illegal.” It was, however, an act of war. So was the attempted breaking of the blockade of Gaza. It is too bad that the blockade runners did not resist with RPGs and machine guns. There would then be no evidence of the nature of the “aid” until salvage operations could be done.
the fact is the boat was in international waters. This is not comparable to the sinking of the SK ship.
The Israelis were not “attacked”. They raided a ship in international waters. The South Koreans lost a boat and 46 citizens in a clear cut case of an unprovoked attack by North Korea.
Frankly I think what Israel did was completely moronic.