Who exactly is the enemy in the continuing U.S. war against terrorism? In some cases, the answer is: It's a secret.
When the United States began its war against al-Qaida after the attacks of Sept. 11, 2001, the identity of the enemy was clear: Osama bin Laden and his followers, and the Taliban who protected them in Afghanistan. Congress quickly passed a resolution authorizing President George W. Bush to use "all necessary and appropriate force" against anyone who "planned, authorized, committed or aided" the 9/11 attacks, plus anyone who harbored them.
That resolution, called the Authorization for the Use of Military Force, remains the legal underpinning for most counter-terrorist operations today.
Since 2001, however, the target list has grown. Al-Qaida offshoots have sprung up in Yemen, Somalia, Libya, Mali and, now, Syria. Many of their members had nothing to do with the attacks of 9/11. Most appear more interested in seizing power in their own countries than in striking the United States. Before he died, bin Laden even scolded his followers in Yemen for spending too much time on local politics and too little on international terrorism.
Nevertheless, both the Bush and Obama administrations decided that the 2001 authorization (the AUMF, for short) covered any group affiliated with al-Qaida that plans operations against the United States or U.S. interests abroad.
In many cases, that's a reasonably clear standard. When al-Qaida's Yemen affiliate put a terrorist with explosives in his underwear on a flight to Detroit, the target was plainly the United States.
But other cases are more ambiguous. Does the Shabab militia in Somalia qualify? They are Islamic terrorists and a danger to East Africa, but they pose little threat to the United States. Does Ansar al-Sharia, the group that attacked a U.S. mission in Libya last year but has loose ties to al-Qaida, fit in? What about al-Nusra Front in Syria, a group born as part of the uprising against Bashar al-Assad? All are violent extremists who might gladly kill Americans given the opportunity. But Congress certainly didn't have them in mind when it approved the AUMF.
"None of us, not one who voted for it, could have envisioned we were voting for the longest war in American history, or that we were about to give future presidents the authority to fight terrorism as far-flung as Yemen and Somalia," Sen. Richard J. Durbin, D-Ill., said recently.
So Congress is, belatedly, pondering whether the 12-year-old law needs to be revised. For some, like Durbin, the problem is that the resolution has turned into a blank check. For others, such as Sen. Lindsey Graham, R-S.C., the problem is that the AUMF doesn't authorize action against terrorists who aren't affiliated with al-Qaida. But both parties agree that Congress ought to take a more explicit role in writing the rules for a war that appears likely to drag on for another decade or more.
At a stormy hearing of the Senate Armed Services Committee last month, Sen. Carl Levin, D-Mich., the panel's chairman, asked if he could see a list of organizations the administration considers al-Qaida affiliates.