Will Congress Amend the WPR by Defining "Hostilities"?

I had thought that the WPR debate in regards to Libya would eventually be eclipsed by a vote on whether to provide supplemental funding to sustain continued operations.  But that, it seems, won't happen.  In a hugely important, and to my mind rather surprising, statement in the documents the White House sent to the Hill yesterday, the administration says:

The Department does not plan to ask for supplemental appropriations and will pay for these costs using currently available Defense funds. These operating costs will be offset through reductions in lower priority support activities, and there will be some reduction to the peacetime flying hour program in part as a result of the Libya operation. The Department plans to replace munitions used in the Libyan operation as part of its normal programming and budgeting process.

Fascinating.  I leave it to the budget experts to decide how plausible this approach will prove to be.  But in any event, it surely suggests that in the short term a debate will not be forced on Congress by the demands of budget constraints.  And so now it seems ever more important that the Administration denies that the WPR clock is running.  That in turn makes me wonder: How long before someone introduces legislation designed to define the key WPR term "hostilities," and more specifically to define it more narrowly than the view just asserted by the administration?  Will we see someone offer an amendment to this effect in connection with the NDAA FY12, for example, which currently is before SASC and still has a long road to go down before enactment? Crafting such a definition would not be an easy task.  On one hand, Congress would not want to cause the WPR clock to start running each time a terrorist attack occurs on some U.S. military facility overseas.  On the other hand, it might be possible to come up with language that keyed in on whether U.S. forces have been authorized to use lethal force other than on a self-defense basis, while either (i) rejecting a requirement that such uses of force be more than episodic or above a certain level of intensity or (ii) defining what degree of frequency or intensity is required to start the clock running.    In any event, I predict we'll see some kind of effort along these lines, sooner rather than later.