For the past couple of weeks, a Saudi-led coalition has been engaged in a substantial air campaign against Houthi forces in Yemen. The United States is not conducting its own air strikes against the Houthis, but it is providing various forms of material and intelligence support to the coalition, including armaments, air-to-air refueling services, satellite imagery, and the posting of a 20-member U.S. military planning cell providing on-site advice and coordination at a Saudi operations center (including the vetting of targets proposed by the Saudis).
Does that support—particularly the vetting of targets—raise any significant legal issues? Some U.S. government officials may think so (or at least thought so early on). According to a story from Reuters that ran last Friday, unnamed government sources
said that data sharing had been extremely minimal in the campaign's early days. That is partly due to legal barriers, the officials said. While the United States has used lethal force against an al Qaeda offshoot in Yemen, it does not consider itself at war with the Houthis. Some officials said the U.S. administration's analysis is that it lacks the ability under international and U.S. law to collaborate with the Saudis in an offensive against the Houthis.
What might those international and domestic legal issues be?
International Law and U.S. Involvement
The reference to international law as a potential obstacle to U.S. participation in the Saudi-led campaign most likely has to do with Yemen’s sovereignty and the U.N. Charter. Might U.S. involvement violate Article 2(4)’s prohibition on the use of force? On close inspection, the question is a bit more complicated than seems at first blush.
Start by considering the position of the Saudis. There is no question that their air campaign is a use of force in Yemen’s territory. The Saudi’s can claim, however, that they have the consent of the legitimate government of Yemen (in the form of the letter President Hadi sent requesting its military assistance—see Nathalie Weizmann’s post on this point), and hence the Article 2(4) issue drops out. Some might quibble with the authority of Hadi to make that request, of course, but otherwise the Saudi position seems strong.
The U.S. position is a bit more complicated. Does U.S. involvement count as a use of force in the first place? It could be that there was initial reluctance to provide target-specific intelligence precisely because it was thought that this would cross the use-of-force line, which would in turn have been a problem if, as explained below, there may have been uncertainty at the time as to whether the United States actually had effective consent from Yemen. The problem with that analysis, though, is that the use-of-force line likely would be crossed in any event once the United States began arming and refueling operations. As Mike Schmitt and Andru Wall explain in their “Unconventional Statecraft” article:
Non-lethal activities (e.g., leadership training, organizational assistance, political or economic intelligence gathering, political subversion, or information operations) do not cross that [use-of-force] threshold. Similarly, logistics support related solely to non-lethal activities (e.g., humanitarian aid) would not reach that level, at least so long as the state’s forces did not violate the territorial integrity of the target state in order to deliver material.
Providing lethal (“military”) training and logistical support, such as instruction on the use of weapons or transporting of rebel forces during operations, would, by contrast, be an unlawful use of force. The provision of arms would unquestionably qualify as such. This was the ICJ’s holding in Nicaragua, which involved U.S. support to insurgents known as the Contras. The Court stated that “the arming and training of the [C]ontras can certainly be said to involve the threat or use of force against Nicaragua.”
In short, it is plain at this point that the U.S. activities supporting the Saudi coalition implicate the U.S. government in a use of force. The issue, then, is whether we, like the Saudis, can invoke Yemen’s consent.
Such consent might take one of three forms: a public request for military assistance from the United States, a private request of that kind, or implicit inclusion of the United States in the request Hadi made to the Saudis.
There does not appear to be a public request from Hadi to the United States, as there is from Hadi to the Saudis and the Arab League. But there certainly might be a private request, and though having the request made publicly has obvious advantages in terms of eliminating doubt on the point, and though some have argued that overtness ought to be a condition for consent to be effective, current law does not require that the request be made publicly. Perhaps there has been no private request either, however. One might argue, in that case, that Hadi’s request to the Saudis, which asks for the Saudis to use “all necessary means,” should be construed as including implicit consent for the Saudis to seek and obtain critical support for those military operations (such as weaponry, fuel, and intelligence) from other states if necessary to facilitate the Saudi’s own operations, even if it would seem implausible to read the request to also include implied consent for other states to conduct kinetic operations themselves.
Domestic Law and U.S. Involvement
The Reuters article also mentioned possible domestic law obstacles to U.S. involvement, in the same breath as mentioning that the United States is “not at war” with the Houthis. This may be a reference to concerns about the source of authority for U.S. participation, however indirect, in kinetic operations. That is: is there statutory authority for it, and if not can it be justified on Article II grounds standing alone?
Consider the statutory possibilities first. Would the 2001 AUMF apply? That seems unlikely. However flexible the AUMF has proven to be, it would be impossible to stretch it to encompass the Houthis as an associated force of al Qaeda or the Taliban. And though the Houthi advance has disrupted U.S. efforts against AQAP to some extent, it would be hard to argue that this fact suffices to bring the Houthis within the AUMF’s reach.
Other statutory possibilities include Title 50 covert action authority and various Title 10 spending authorities. The Title 50 argument is inapplicable insofar as we are speaking of acknowledged U.S. government activities, of course. Title 10 spending authorities, in contrast, may well be applicable as to some of the activities in issue here, particularly to the arms transfers. But it is hard to see how they would authorize the participation of U.S. personnel in target selection/vetting.
Which brings us to Article II, and the argument that any necessary authority flows from a combination of commander-in-chief and foreign-affairs powers. Whether that argument works turns in no small part on whether one thinks that this degree of involvement in an armed conflict rises to a level that at least implicates Congressional prerogatives.
It may help to consider the following: There is a spectrum of intensity that runs from run-of-the-mill peaceful circumstances to large-scale, direct involvement in sustained combat operations.
At the peaceful end of that spectrum, it seems clear that the President’s commander-in-chief authority (and perhaps other Article II authorities as well, such as the President’s authority in foreign affairs) allows him to direct the movements and activities of U.S. military personnel abroad, including activities conducted jointly with foreign militaries; it happens all the time, and is not generally seen as a separation of powers issue. So too with respect to the Intelligence Community sharing information with foreign partners. Conversely, at the high-intensity end of the spectrum in which the U.S. military engages directly in war, important (and hotly-contested) questions arise with respect to whether and to what extent Congressional authorization is required.
What makes the current situation interesting, of course, is that it falls into something of a grey area on that spectrum. It is a low-intensity, indirect form of participation in a conflict, to be sure, and thus it seems likely that the administration would take the view that this simply falls below the threshold that calls into question the President’s capacity to act independently. Considering that the administration took the view that actual U.S. airstrikes did not cross that threshold in Libya in 2011, it is easy to imagine the same conclusion being reached in this case, where the U.S. role is much more limited.
One might distinguish the 2011 Libya example by pointing out that, in this case, there is no U.N. Security Council Resolution in play, nor any serious attempt to claim that the airstrikes are designed to stave off an imminent humanitarian disaster. This does indeed subtract from the affirmative case that substantial national interests are at stake. On the other hand, one might argue that the Yemen situation more strongly implicates other aspects of the national interest, including the sustaining the Hadi regime in order to advance counterterrorism interests involving AQAP, containing Iranian influence, and avoiding further regional instability. These interests, in combination with the very limited nature of the U.S. role, likely explain why the administration has overcome any domestic law concerns it may have had, as an initial matter, in supporting the Saudi-led coalition.