Here is a link to the San Remo Manual on International Law Applicable to Armed Conflicts at Sea:
http://www.icrc.org/...
I believe that according to Articles 102(b) and 103(b), regarding the prohibition of blockades and the correct methods of allowing supplies through, Israel almost certainly violated International Humanitarian Law in its recent boardings of humanitarian ships headed towards Gaza. It is important to use the San Remo Manual because many are claiming that it actually allows Israel to board these ships, and even to attack the crew members.
The complete section of the San Remo Manual on blockades, and my take on that section and a few others, is below the fold.
Here is the complete section regarding blockades:
Section II : Methods of warfare
Blockade
- A blockade shall be declared and notified to all belligerents and neutral States.
- The declaration shall specify the commencement, duration, location, and extent of the blockade and the period within which vessels of neutral States may leave the blockaded coastline.
- A blockade must be effective. The question whether a blockade is effective is a question of fact.
- The force maintaining the blockade may be stationed at a distance determined by military requirements.
- A blockade may be enforced and maintained by a combination of legitimate methods and means of warfare provided this combination does not result in acts inconsistent with the rules set out in this document.
98. Merchant vessels believed on reasonable grounds to be breaching a blockade may be captured. Merchant vessels which, after prior warning, clearly resist capture may be attacked.
- A blockade must not bar access to the ports and coasts of neutral States.
- A blockade must be applied impartially to the vessels of all States.
- The cessation, temporary lifting, re-establishment, extension or other alteration of a blockade must be declared and notified as in paragraphs 93 and 94.
102. The declaration or establishment of a blockade is prohibited if:
(a) it has the sole purpose of starving the civilian population or denying it other objects essential for its survival; or
(b) the damage to the civilian population is, or may be expected to be, excessive in relation to the concrete and direct military advantage anticipated from the blockade.
103. If the civilian population of the blockaded territory is inadequately provided with food and other objects essential for its survival, the blockading party must provide for free passage of such foodstuffs and other essential supplies, subject to:
(a) the right to prescribe the technical arrangements, including search, under which such passage is permitted; and
(b) the condition that the distribution of such supplies shall be made under the local supervision of a Protecting Power or a humanitarian organization which offers guarantees of impartiality, such as the International Committee of the Red Cross.
104. The blockading belligerent shall allow the passage of medical supplies for the civilian population or for the wounded and sick members of armed forces, subject to the right to prescribe technical arrangements, including search, under which such passage is permitted.
This is all meant to determine the legality of the Israeli actions in recent days, not as any statement on the morality of their actions.
According, then, to article 98, which is what Israel and others are touting, the Israelis could legally "attack" the ship since it obviously was headed towards Gaza in an effort to breach the blockade. I find the attack certainly disproportionate and inhumane, but let's leave that aside. I think the question of the attack coming in "international waters" is immaterial because of the fact that the flotilla was obviously headed towards Gaza.
(See also Part II, Section I, which does clearly state that actions in "Neutral Waters" are forbidden by belligerents. However, "Neutral Water" refers to the waters of "Neutral States" and not to "international waters." "International Waters" is only once mentioned in the Manual, under the section on mine warfare.)
However, article 102(b) clearly shows that, at least from what I've seen and heard, the blockade is unquestionably illegal. The "military goal" of prohibiting weapons into Gaza does not justify the starvation of the people, the deprivation of allowing trade there, nor the blockading of building materials in order to rebuild buildings that were destroyed by the Israelis in previous conflicts. Anyone claiming that there "is no humanitarian crisis" in Gaza is being willfully ignorant. Because the blockade is illegal, no merchant ships are under any obligation to obey the Israelis. All force would then be illegal.
The argument that Israel claimed it would "escort" the supplies from Ashdod falls through under article 103(b). As far as I know, the Israelis never claimed that they would allow either the UN or the ICRC or any other humanitarian organization to supervise the transfer of goods into Gaza. Because the Israelis never guaranteed any of the flotillas the supervision of their goods by an independent humanitarian organization, the flotillas (and this is assuming that the blockade is legal anyway, which it isn't) had no reasonable assurance that their aid would reach Gaza, and therefore had no reason to comply. The Israelis thus had no rationale to board the ship, attack its members, search the ship, jam their communications, hinder their passage, etc. etc., since they never guaranteed independent supervision.
(I will say that it is questionable under the San Remo Manual article 104 whether Israel had to allow the medical supplies to be supervised by an independent humanitarian organization. It seems implied, but it isn't explicitly stated, as in 103(b). Because the blockade is illegal, the question is beside the point, but theoretically, it's hard to tell what protocol would be for a ship that was carrying both foodstuffs, necessary objects, AND medical supplies. However, if medical supplies can be considered "necessary objects," and article 104 is intended for the simple passage of ANY medical supplies, a lack of medical supplies in Gaza [which is a fact] would then allow medical supplies to fall under the purview of article 103 as being necessary to the civilian population's survival, and thus subject to independent supervision.)
Article 136 also clearly prohibits the capturing of humanitarian vessels. The only question becomes whether, according the article 137(a), the aid is "innocently employed in [its] normal role." If not, it is subject to capture in a legal blockade. Because no legitimate weapons have been released (and pocket knives and poles do not count), I would say the mission was "innocent."
amad's diary provides further information.