ASIL Insights

The United Nations Charter recognizes "the inherent right of self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security."  The Charter does not expressly limit the right of self-defense to attacks by one state against another, but that is the context in which the right was established in international law up to and including World War II.  One might therefore ask in the current context whether the Palestinian Authority represents a state, such that it would be capable of an armed attack that could trigger Israel's right of self-defense.  The answer seems to be that if a political body has the attributes of a government of a population in a reasonably well defined territory, it could be considered capable of perpetrating an armed attack under international law, whether or not it is a state that has been officially recognized by other governments or by the United Nations.

If the Palestinian Authority is legally capable of an armed attack, it remains to be seen whether it has actually committed such an attack.  The Palestinian Authority has not invaded Israel with an army or other organized military force.  But if it has harbored or supported groups engaged in terrorist acts in Israel, it could be said to be in a position comparable to that of the Taliban in Afghanistan if-as the United States and others believe-the Taliban supported the al-Qaeda terrorist group thought to be responsible for the September 11 attacks on the World Trade Center and the Pentagon.  The United States has relied on its right of self-defense in using military force to respond to the September 11 attacks.  Other governments have not challenged the right of the United States to do so, although some questions have been raised about U.S. tactics and targeting.  Because customary international law is often developed through a process of official assertions and acquiescences, the absence of challenge to the US asserted right of self-defense could be taken to indicate acquiescence in an expansion of the right to include defense against governments that harbor or support organized terrorist groups that commit armed attacks in other countries.

The terrorist bombings in Israel on December 1 and 2 did not approach the intensity or destruction of life and property caused by the attacks on the World Trade Center and the Pentagon.  The question thus arises whether they could amount to "armed attacks" even if one concludes that the US response to the events of September 11 could serve as a legally-significant precedent that helps to define "armed attack" and to justify a concentrated military response to a terrorist attack.  The Israeli government would argue that the bombings of December 1 and 2 should not be viewed in isolation: instead, they must be considered as an escalation in an ongoing course of terrorist acts in Israel and against Israeli citizens.  The question then would be whether the ongoing course of terrorism, now raised to a new level, amounts to an armed attack on Israel.  There is no definitive precedent or rule that would answer this question.  The responses of other governments to the Israeli course of action will be relevant to the development of international law in the terrorism context and to any assessment of the legitimacy of Israel's intensified military campaign.

If Israel is legally entitled to act in self-defense in response to the course of terrorist acts, a question remains as to whether its response is proportional to the use of force against which it is defending.  Customary international law requires proportionality in the exercise of a right of self-defense, but it is not precise as to how proportionality is to be measured.  Proportionality could mean either of two things.  It could mean that the intensity of force used in self-defense must be approximately the same as the intensity defended against.  Or it could mean that the force, even if more intensive than that, is permissible so long as it is not designed to do anything more than protect the territorial integrity of the defending state.  The World Court had an opportunity to shed some light on this issue in the case of Nicaragua v. United States, but it failed to articulate a meaningful standard that could be applied to other cases. [1]  Israel's position would be stronger under the second definition than under the first.

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ASIL Insights are intended to identify international law issues in order to provide a basis for informed discussion of current events. They are not intended to be definitive, and they do not necessarily reflect the views of all members of The American Society of International Law. The Society itself takes no position on these issues.