Who is a terrorist?

Who is a terrorist “affiliated” with al-Qaeda?

Who is really affiliated with al-Qaeda, and who in turn threatens the United States?

And what does the United States do about any of it?

These hard questions must be confronted. And they’re being dealt with daily at various levels of the government — with varying responses.

One day after the State Department declared it a terrorist organization because of its support from al-Qaeda in Iraq (AQI), the militant Syrian group Jabhat al-Nusra announced that it had formed its own mujaheddin council.

Considered one of the most capable fighting rebel forces, al-Nusra “has sought to portray itself as part of the legitimate Syrian opposition, while it is in fact an attempt by AQI to hijack the struggle of the Syrian people for its own malign purposes,” State Department spokeswoman Victoria Nuland said Tuesday.

On Wednesday, Iran’s Fars news agency reported that Bashar al-Assad’s army, which Tehran supports, had caused “heavy casualties” to al-Nusra, which it referred to as “affiliated with the al-Qaeda terrorist organization.”

Tuesday evening, President Obama announced that the United States would recognize the Syrian Opposition Coalition as the sole legitimate representative of the Syrian people. Without singling out al-Nusra, Obama said: “Not everybody who’s participating on the ground in fighting Assad are people we are comfortable with. There are some, I think, who have adopted an extremist, an anti-U.S. agenda, and we are going to make clear to distinguish between those elements.”

The United States opposes al-Nusra; Assad’s army and the Iranians who support it also oppose al-Nusra; in fact, they are killing its members. It remains to be seen what the newly recognized Syrian rebel coalition will do about al-Nusra.

Meanwhile, there is the question of what the United States can do about AQI, which has had a resurgence in Iraq. As The Washington Post’s Joby Warrick reported Dec. 2, Jordanian plotters in Amman — before they were caught — were aided by AQI “using the terrorist group’s expertise and weapons from Syria’s civil war.”

Warrick quoted Bruce Riedel, a former CIA counterterrorism expert who is with the Brookings Institution, saying, “What we’re now seeing is al-Qaeda in Iraq’s revival, not only as a movement in that country but as a regional movement.”

On Dec. 6, Defense Secretary Leon E. Panetta and Iraqi Defense Minister Sadoun al-Dulaimi signed a five-year memorandum of understanding that mainly deals with cooperative efforts, including high-level visits and education exchanges but also “counterterrorism cooperation and the development of defense intelligence capabilities.”

One of the newest dilemmas for the United States is what to do about Mali, where beginning in January separate groups in the northern part of the country seized areas that total the size of Texas. They defeated Malian army forces and set themselves up as governors.

Three of the groups have roots in the area. A fourth, al-Qaeda in the Islamic Maghreb (AQIM), is a militant Sunni group with roots in the Algerian civil war against France. It formally linked up with al-Qaeda in September 2006, according to the U.S. National Counterterrorism Center.

Its prime targets have been mainly in Algeria, but its activities — including kidnapping and narcotics trafficking — have spread to other countries. It also claimed responsibility for killing an American missionary in Mauritania in June 2009. More recently, people associated with AQIM were said to have taken part in the attacks on the U.S. mission in Benghazi, Libya.

Attempts to negotiate with the breakaway groups, other than AQIM, were complicated in March. That’s when disaffected soldiers from the Malian army overthrew the government and set up a junta under Capt. Amadou Sanogo. Sanogo was supposed to relinquish power, but he didn’t, even though a provisional president and prime minister were established with plans for elections.

The United Nations, in cooperation with the African Union, the Economic Community of West African States and various countries, including the United States, has been trying to mediate the situation. These efforts include preparations for a multinational military force to dislodge AQIM if diplomacy does not work.

The plan calls for the operation to be led by Malian commanders, with 5,000 Mali troops and another 3,300 troops from other countries.

However, the Malian forces would take months to train, and it is unclear where the other troops would come from. Who would pay for the operation? As planned, it would also include a period of counterinsurgency to make sure that anti-government elements did not return.

Planning hit another roadblock Tuesday when Sanogo arrested the provisional prime minister and forced him to resign.

As the United States attempts to deal with terrorist threats around the world, it is worth thinking about those first three questions.

For previous Fine Print columns, go to washingtonpost.com/fedpage.