An Israeli F-16 jet takes off on December 9, 2014 at the Ovda airbase in the Negev Desert near Eilat, southern Israel. (Lior Mizrahi/Getty Images)

On Tuesday, January 9, Israel reportedly attacked an arms depot at a Syrian military base near Damascus with both jets and ground-to-ground missiles. The strikes have thus far met with deafening silence from the international community and from Israel itself. This silence is a worrisome sign for the health of the prohibition on unilateral use of force and the international legal order that depends on it.

A full week has passed since the attacks, and Israel still has not formally acknowledged or commented on the strikes, but Prime Minister Benjamin Netanyahu said during a lunch with NATO ambassadors in Jerusalem last week that, “[w]e have a long-standing policy to prevent the transfer of game-changing weapons to Hezbollah from Syrian territory. This policy has not changed. We back it up as necessary with action.”

This is not the first time this has happened, of course. Asaf Lubin pointed out in Just Security in May 2017 that even as international lawyers jumped to dissect the legality of U.S. strikes on Syrian military targets which took place the previous month, almost no one wrote about Israeli attacks on warehouses near the Damascus airport around the same time.

This is all the more notable because Israel’s attacks appear to be on very thin legal ice under international law.  Because Israel has not acknowledged, much less defended, the strikes, it is difficult to know what argument its lawyers would make. But here are some candidates:

(1) Israel is already “in a state of war” with Syria.

Ernesto Sanchez in an Opinio Juris post in June argued that the conflict between Syria and Israel that began with the 1967 war never came to an end. The parties agreed to a UN-brokered cease fire at the close of that conflict, and then again at the close of the Yom Kippur War.  But a cease fire, he argues, cannot end the war under international law. Therefore, the war never ended.  And because it never ended, the continued state of war between Syria and Israel justifies Israel’s periodic strikes.

The argument, however, fails to hold up. The key problem is that it assumes that states continue to have the right to launch attacks at one another as long as there is a “state of war.” This is an outmoded way of conceptualizing jus ad bellum. As Scott Shapiro and I show our book, The Internationalists, war once was a legal and legitimate means of resolving disputes.  But that’s no longer true. The mere existence of an official state of war is no longer a justification—by itself— for the use of force. Today, states may only use force “against the territorial integrity or political independence of any state” for reasons authorized in the UN Charter framework:

1) If the use of force is authorized by the UN Security Council.

2) As an exercise of “the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations,” as recognized under Article 51 of the charter.

3) Where the host state consents to the use of force (such a use of force does not violate Article 2 in the first instance because it is not “against the territorial integrity or political independence of any state”).

The first and third conditions clearly have not been met, so Israel could only use force against Syria if it has a legitimate self-defense justification.  Moreover, if the Israeli attack is understood as an attack on Syria, then Israel needs to show that it has suffered an armed attack or expects an imminent attack by Syria. (And it would need to file a letter with the UN explaining this legal position under Article 51 — something it has not done.) There’s also another reason the “war never ended” argument might be an unattractive one for Israel to embrace: If Israel can legally strike Syria because the war never ended, then presumably Syria can legally strike Israel, as well.

(2) Israel is acting in self defense against Hezbollah, as permitted under Article 51 of the UN Charter.

U.S. Air Force Maj. Gen. (ret) Charles J. Dunlap* has defended Israel’s earlier strikes in Syria as a legitimate act of “anticipatory self defense” against Hezbollah, on the theory that the strikes are designed (as Netanyahu suggests) to prevent delivery of weapons to that organization. According to Dunlap, Hezbollah’s history of hostile actions against Israel, as well as its adoption of a technique of embedding weapons in densely populated areas once they enter Lebanon, mean that the weapons depot in Syria “might be the last ‘clear opportunity to act’ before the weapons could be embedded into civilian areas in easy range of Israel where they could be countered only at great risk to noncombatants.”

Citing the Obama administration’s December 2016 Report on the Legal and Policy Frameworks Guiding the United States’ Use of Military Force and Related National Security Operations, Dunlap argues that “it would be hard not to conclude that the strike would fit the criteria” justifying self-defense in the face of an imminent threat. The criteria to which he refers, and which the report cites, come from Daniel Bethlehem’s influential article, Self-Defense Against an Imminent or Actual Armed Attack by Nonstate Actors, which reportedly summarizes the results of conversations between the United States and its allies on the imminence standard for self-defense. That description of the imminence standard for self defense, however, is not without its critics.

Even accepting for the sake of argument that the principles Bethlehem detailed are a correct statement of the law and that the Israeli strikes in Syria were intended to destroy weapons intended for immediate transfer to Hezbollah, it is far from clear that the strikes could pass legal muster.  The second Bethlehem principle states that, “[a]rmed action in self-defense should be used only as a last resort in circumstances in which no other effective means are reasonably available to address an imminent or actual armed attack.”  Hezbollah’s tactic of embedding weapons in densely-populated parts of Lebanon to which Charlie refers is more attenuated than this principle would seem to require. Stretching the definition of “imminence” in self-defense to include the provision of weapons that will be transported to a less-accessible location for a possible future armed attack would seem to rob the “imminence” requirement of any effect. The third Bethlehem principle states, “[a]rmed action in self-defense must be limited to what is necessary to address an imminent or actual armed attack and must be proportionate to the threat that is faced.” So far, it has not been established that the decision to launch an attack on weapons depots in Syria was, in fact, “necessary” to address an imminent attack by Hezbollah against Israel. Again, the causal chain appears too attenuated. For these reasons, I am less persuaded than Dunlap is that Israeli attacks on weapons located in a third country possibly intended for later transfer to Hezbollah meets even the Bethlehem principles—which, again, many regard as already stretching the imminence standard too far.  Kevin Jon Heller, in a post responding to Dunlap, similarly finds the argument that Israel’s strikes meet the standard for self defense less than compelling. (And it is again worth noting that Israel would need to file an Article 51 letter with the UN explaining this legal position, if this is its position—which it has not done.)

It may very well be that Israel knows that the strikes are illegal and that is why it has not acknowledged them or attempted to explain or defend them, other than obliquely. Does that mean we should be less concerned?  After all, some have suggested that unacknowledged attacks of this kind do not create customary law precedent.

But whether or not unacknowledged strikes create a formal legal precedent or not, strikes in violation of international law are corrosive of the legal order. As Scott Shapiro and I argue at length in The Internationalists, the modern legal order is grounded in the foundational principle that states cannot use force against one another except in very limited circumstances.  The refusal by a striking state to acknowledge or defend attacks that violate the prohibition on unilateral uses of force does not erase the damage they do to that rule.  Instead, such strikes and their disregard for international law put the legal order at risk at a moment when it is already under assault from many quarters.  Indeed, the Israeli strikes over the past year may be a sign that the Trump administration is willing to tolerate actions by allies that violate the UN Charter. (Don’t forget, that the Trump administration undertook its own illegal strikes on Syria in April 2017).  And that may be the most worrisome sign of all.


* Correction: This post has been updated to accurately reflect Charles Dunlap’s rank upon retiring from the military.