(CNN) -- It was the most ambitious and the deadliest terror attack since the rampage by Pakistani militants through Mumbai five years ago. And it raises the alarming prospect that al Qaeda affiliates and other jihadist outfits could turn parts of northern and western Africa into no-go zones -- places too dangerous for Westerners to work, or even visit.
The attack on the In Amenas gas facility left 37 foreign workers dead, according to the Algerian prime minister. It showed that al Qaeda-linked groups now have the resources to reconnoiter and launch complex attacks against places far from their strongholds, using a network of camps and intermediaries throughout the desert.
If their rhetoric is to be believed, their goals include targets farther afield -- leveraging sympathizers among the vast North and West African diaspora in Europe.
A spokesman for the man who orchestrated the attack, Moktar Belmoktar, told French media Monday that France would see "dozens like Mohamed Merah and Khaled Kelkal." Merah shot dead seven people in Toulouse, France, last year; Kelkal carried out a series of attacks in France in 1995.
Oil companies reassess risk
The most immediate concern to counterterrorism analysts is that Belmoktar will launch more attacks against Western companies in North Africa. A second attack on oil and gas infrastructure could cause foreign oil companies to reassess their exposure in Algeria, Libya and parts of West Africa, or at least raise the security costs of doing business in the region.
A former head of intelligence for the Transitional National Council in Libya, Rami El Obeidi, told CNN last week that with the French intervention in Mali, "a Pandora's box has been opened," and he believes oil fields in Libya are also at high risk of being attacked.
Geoff Porter, a longtime observer of events in North Africa, says a mass exodus of Western companies from Algeria is highly unlikely. But, he said, "the Algerian hydrocarbons sector will enter a holding pattern for the next month or so, possibly resuming meaningful activity at the beginning of March."
"Companies looking at potential opportunities in Algeria will now look not only at the available acreage's prospectivity, but also how its location impacts security concerns and associated costs," Porter added.
Belmoktar, the leader of a newly formed Saharan al Qaeda franchise that split from al Qaeda in the Islamic Magrheb (AQIM) last fall, remains at large, likely hunkering down in northern Mali, where he is believed to have amassed weapons and a war chest of millions of dollars from ransom payments and smuggling.
Belmoktar has been based in or near the town of Gao, where endless tracts of desert as well as cave complexes have been a safe-haven for a variety of militant groups affiliated with al Qaeda since armed Islamist rebels drove out government forces early last year.
Last month he announced the formation of a new commando unit called Those Who Sign with Blood.
"He has all the resources he needs in terms of money, weapons and soldiers to launch new attacks, and his recruitment and fundraising efforts will likely be boosted significantly because of the attack," said Noman Benotman, himself a former Libyan jihadist who is now a senior analyst at the Quilliam Foundation in London.
Belmoktar became known as "Mr Marlboro" because of his smuggling enterprises. But Robert Fowler, a Canadian diplomat who was held for 130 days after being taken hostage by Belmoktar in 2008, said he had no doubts about where Belmoktar's priorities lay.
"His men were amongst the least materialistic I ever encountered. His criminality always served the expansion of jihad," he told CNN.
According to Benotman and other sources, the leader of the Algerian attack was Taher Ben Cheneb, the Algerian head of The Movement of Islamic Youth in the South. In his 50s, Cheneb was a longtime associate of Belmoktar. Cheneb was supported by Abdul Rahman al Nigeri, from Niger, and another Algerian, Abou al Barra.
The unit Belmoktar dispatched was well-armed: heavy machine guns, assault rifles, rocket-propelled grenades, mortars and explosives were recovered from the scene. And eyewitness accounts suggested the group or supporters had undertaken advance surveillance because it was apparent the attackers were familiar with the sprawling facility.
U.S. officials and North African sources believe the attackers entered Algeria from Libya and that some may have been trained in jihadist camps in southern Libya, not far from the In Amenas gas facility. The sources tell CNN that Libyan authorities are aware of three jihadist camps south of Sabha providing instruction to militants from North Africa and the Sahara, but have lacked the capability or will to move against them.
According to one source, Belmoktar visited the commandant of one of these camps on a trip he made to Libya in late 2011.
Benotman says the first phase of the assault involved an attempt to hijack a bus carrying Westerners as it traveled to the local airport. This would have required advance knowledge of travel arrangements. Benotman told CNN that in the view of regional security officials, the attackers likely received some insider help -- they also knew which units at the facility housed foreign workers.
Algerian Prime Minister Abdelmalek Sellal said Monday insider knowledge was passed on by a Niger national who had previously worked as a driver at the facility.
"If there was an 'inside man,' then this has certain implications for due diligence and vetting of employees at other oil and gas sites," according to Geoff Porter, who runs North Africa Risk Consulting Inc.
The attackers' plan, according to Benotman, was likely to take hostages from the bus across the nearby border into Libya, although he said it is possible their final destination could have been another neighboring country, such as Mali.
But the intervention of Algerian forces prevented their escape. The second part of the plan appears to have been to threaten to kill the workers if the Algerians tried to storm the complex.
"If the attack was a genuine attempt to seize hostages, then this raises the likelihood that there will be another attempt at another facility," Porter said.
"The same implications apply if the goal was to destroy the facility. If, however, the attack was a 'spectacular' aimed at raising the profile of Moktar Belmoktar in the Sahara, which appears to be the most likely interpretation at this point, then the likelihood of it being repeated is lower," he added.
A jihadist spring
The attack on the Algerian compound involved fighters from across North Africa and the Sahara, according to Algerian authorities, including from Egypt, Mali, Niger, Mauritania, Tunisia and Algeria.
"Belmoktar's group in particular appears to have evolved -- they've been able to attract a more diverse group of foreign fighters than before, and that's a reflection of how other jihadists see them," said Andrew Lebovich, a Senegal-based security analyst.
Several other jihadist groups have also expanded, including factions of AQIM, a hotchpotch of jihadist militias in Libya, and the Nigerian militant groups Boko Haram and Ansaru. A variety of North African and Saharan jihadists and even some Nigerian militants appear to have received training in northern Mali, according to Lebovich, with different groups in the region "cross-fertilizing."
Sources monitoring the security situation in eastern Libya say that, if anything, it has worsened since the attack on the U.S. diplomatic compound in Benghazi in September, with a series of assassinations and attempted assassinations of security officials, many of which are blamed on Islamist militants.
Libyan authorities are aware of several jihadist camps providing instruction to Libyan militants and foreign fighters in the Derna and Benghazi region, but have not had the firepower to move against them. According to Western intelligence officials, a leading jihadist operating in the area is Abdulbasit Azuz, dispatched to Libya in 2011 by al Qaeda leader Ayman al-Zawahiri.
The Nigerian group Ansaru claimed responsibility for an attack that killed Nigerian troops heading to Mali on Sunday.
"We are warning the African countries to (stop) helping Western countries in fighting against Islam and Muslims or face the utmost difficulties," the group stated. Last year, White House counterterrorism advisor John Brennan warned that Ansaru was committed to transnational jihad.
Terrorism analysts believe that following the Algeria attack and the French military operation in Mali, these groups may be inspired to launch attacks against Western interests in the region.
"Fighting against local governments didn't help them. It didn't create the euphoria they needed. But now they have this foreign element: an invasion, the West, Crusaders giving them a sense of meaning and a cause in exactly the way Osama bin Laden envisioned," Benotman told CNN.
In recent days, Benotman said, hardline Salafist preachers across the Arab world have declared a call to arms against the French military intervention, depicting it as a foreign occupation.
Western governments are under no illusions regarding the challenges that lie ahead in the region.
"It will require a response that is about years, even decades, rather than months, and it requires a response that is patient, that is painstaking, that is tough, but also intelligent," British Prime Minister David Cameron said Sunday.
Although in the long term the Arab Spring may discredit al Qaeda's violent ideology, jihadist groups have taken advantage of political turmoil and the dismantling of security services in North Africa to build up their operations.
Over the past two years, al Qaeda has shifted its center of gravity from the Afghanistan-Pakistan border region where it is under pressure from drone strikes toward the Arab world, green-lighting the return of dozens of Arab operatives to their homelands, according to Western intelligence officials. The emergence of Syria as a new jihadist cause celebre has further energized militants.
In announcing the formation of the commando unit in December, Belmoktar had promised attacks on Western interests in the region and the home soil of Western countries if they moved against jihadists who had taken over northern Mali.
The fact that some of the attackers in Algeria were carrying Western identification -- two of them were reportedly Canadian -- will raise concern that the group could retask such recruits to launch attacks in the West.
Algerian Prime Minister Sellal said Monday a Canadian national known only as Chedad had played a coordinating role in the attack.
"French security officials have publicly said for some time that they are especially concerned that Westerners could come back from North Africa or the Sahel to launch attacks," Lebovich told CNN. The Sahel is the area along the southern edge of the Sahara.
So far, neither Belmoktar's group nor any other al Qaeda faction in North Africa has come close to launching a terrorist attack in Europe. Virtually all the AQIM cells dismantled in Europe were focused on logistics and fundraising rather than plotting terrorist attacks, according to European counterterrorism officials.
Confronting this emboldened transnational jihad in north Africa is a daunting task, complicated by several factors.
One is the long-standing lack of cooperation between North and West African countries. Algeria and Morocco, for example, are rivals for influence. Another is competing priorities among regional governments. Western diplomats tell CNN that Nigeria, for example, is more concerned about the threat from Boko Haram within than jihadist safe havens in Mali.
There is also the long experience of operating in the desert that leaders such as Belmoktar have, and the complex relationships between different and often fractious groups.
Another factor is that the United States has not developed the sort of intelligence infrastructure in this region that it painstakingly built up in the tribal areas of Pakistan and Yemen. In December, U.S. officials began discussing with Algeria the possibility that it might acquire its own satellite surveillance system to monitor terrorist movements in southern Algeria.
Analysts warn that however successful the first phase of the French operation in Mali, it is likely to encounter challenges similar to those faced by U.S. and British forces in Iraq as the campaign evolves.
"For months jihadists in Mali have been preparing for a military intervention by creating a network of hundreds of weapons caches and safe houses in the desert where they've stored weapons, ammunition, and food and set up communication channels," Benotman told CNN.
He said Belmoktar in particular may be hard to track down. "He's a survivor -- he knows when to go into hiding when necessary," he told CNN.
That's why French intelligence officials have dubbed him "The Uncatchable."