Is the Obama Administration Relying on Article II for Targeted Killing?

A few days ago I argued that the Obama administration’s eschewal of the Bush administration Article II argument in its detention litigation was not as big a deal as it seemed.  Now I want to explain why I think the Obama administration might be relying, or preserving, the Article II argument in a different context – targeted killing.  In his carefully worded defense of the Obama targeted killing program, Legal Advisor Harold Koh said:

[S]ome have argued that our targeting practices violate domestic law, in particular, the long-standing domestic ban on assassinations.  But under domestic law, the use of lawful weapons systems—consistent with the applicable laws of war—for precision targeting of specific high-level belligerent leaders when acting in self-defense or during an armed conflict is not unlawful, and hence does not constitute “assassination.”

The legality of targeted killing under domestic law is relatively straightforward for persons involved in the armed conflict initiated by the congressional AUMF, which authorized the President to use force against persons within the AUMF’s scope.  What is significant about the Koh statement is the claim that targeted killing would also be lawful under domestic law as an exercise of self-defense. Past presidents have made self-defense and related arguments under domestic law when using military force abroad pursuant to Article II powers, without approval of Congress.  For example, President Clinton’s 1998 missile strikes in Afghanistan and Sudan were justified on this basis, as were President Reagan’s 1986 strikes in Libya.  An even more salient example is the planned capture and kill action against Osama Bin Laden in 1998.  According to the 9/11 Commission Report (pp 131-133 & n. 122-123), the Clinton administration approved this action, in the absence of congressional authorization (and thus presumably under Article II), reasoning that it would be consistent with the assassination ban because “killing a person who posed an imminent threat to the United States would be an act of self-defense, not assassination” (my emphasis).
This is why I think that Koh’s mention of self-defense as a domestic legal rationale independent of the armed conflict (i.e. AUMF) rationale might indicate that the Obama administration is relying on, or preserving, the Article II argument as a basis for targeting killing.  Relying on or preserving such an argument would be consistent with reports that there is debate within the administration about the proper scope and limits of the AUMF.  If the administration wanted to target terrorists who pose a serious threat to the United States but who do not easily fall within the scope of the AUMF, self-defense under Article II would be the most obvious alternative domestic law rationale.
There would be nothing untoward about relying on Article II in this context; as noted, there are many precedents.  But it would be very interesting if the Obama administration – which has taken great care in public to avoid Article II – were relying on or even preserving Article II in this way.  And it would be even more interesting for Harold Koh to be the administration’s mouthpiece for this argument.  For Koh has for decades been a leading opponent of the President using military force abroad, under Article II, in the absence of congressional authorization.  These factors make me think I may be missing something.  If anyone can figure out another way to parse the “self-defense” language in this part of Koh's speech, please let me know.  But perhaps I am right, and perhaps Koh had the Article II argument in mind when he emphasized in his speech the constraints of executive branch precedent, and said this:  “[T]he making of U.S. foreign policy is infinitely harder than it looks from the ivory tower. . . . In this maze of bureaucratic politics, you are only one lawyer, and there is only so much that any one person can do.”