"They are the jihadi organization that has been the farthest in this path. It is very peculiar to AQIM," Filiu said.

U.S. officials say they believe ransoms that other Western nations have paid for the release of AQIM's hostages are its primary source of funds. Next in line is income from smuggling, largely moving Latin American cocaine along routes that take it to Europe.

Army Gen. Carter Ham, head of the U.S. Africa Command based in Stuttgart, Germany, has been the U.S.'s most vocal official proclaiming the AQIM threat.

"We view the threat posed by al Qaida in the Islamic Maghreb as a very serious threat not only to African people but to us as well," Ham told a group of Senegalese journalists in late August.

A month later, he told the Defense Writers Group in Washington that intelligence estimates suggested that al Qaida's global affiliates and emulators, including AQIM, Boko Haram in Nigeria and the Shabab movement in Somalia, may be gaining strength even as the core al Qaida command is weakening.

"That's what I see in Africa and that's what concerns me in Africa," said the general.

While this summer's wave of attacks in Algeria showed the group's northern wing was still active, it's the group's expansion south that most alarms Washington.

The move into what is known as the Sahel — the sparsely-vegetated belt squeezed between central Africa's tropics and the great Sahara — was spurred by a mix of desperation and opportunism: a crackdown by Algerian authorities in 2008 severely weakened the group, but the desolate Saharan dunes, porous borders, and weak governments to the south also proved a vast safe haven and valuable pot of funds.

Now there are worries that the group is strengthening its ties to black Africa, and other like-minded jihadist groups, Nigeria's Boko Haram in particular. The Aug. 26 blast in Cherchell came just a few hours after a more headline-grabbing suicide attack by Boko Haram against the headquarters of the United Nations in Abuja, Nigeria's capital, that killied 23. On Saturday, a blast that killed 67 Nigerians was blamed on Boko Haram.

In Washington, Ham said the intent to collaborate was especially strong between AQIM and Boko Haram, which was being blamed for Saturday's blast that killed 67 people in Nigueria.

That, however, is not a universally held opinion, even within the U.S. government. A State Department official specializing on security in the region downplayed the links between the groups, calling the contacts between the two "episodic."

Andrew Lebovich, an analyst at the New America Foundation, a non-partisan Washington think tank, says "the public evidence" of collaboration "is too thin to draw that kind of conclusion."

"The U.S. and other governments seem pretty convinced, but it's pretty difficult to confirm without access to the classified material," he said.

Boko Haram remains a very Nigerian organization, and AQIM — despite its global jihadist rhetoric — remains largely Algerian-focused, with an Algerian leadership, he notes.

Some analysts point out that regional governments have an incentive to play up the terrorist threat in their countries — attracting more Western aid. That effect could have been on display when in September, when the government of Niger took advantage of the rare presence of foreign reporters covering the arrival in Niamey of Moammar Gadhafi's son Saadi to announce a major clash with AQIM forces in northern Niger in which it claimed to have captured 59 recruits.