Belmokhtar, designated a foreign terrorist by the U.S. as far back as 2003, is an Algerian who fought against the Soviets in the 1979-89 Afghanistan war, where he lost an eye in combat.
He also fought in the decade-long Algerian civil war between Islamists and the military government that began in 1992, which spawned a generation of hardened guerrilla fighters.
The United States and Europe are concerned long-term turmoil in North Africa could provide room for al-Qaida to set up bases in the region, an hour's flight across the Mediterranean from Spain, France and Italy, as it did in Afghanistan, Somalia, Yemen, Iraq and most recently war-torn Syria.
The anarchy that has gripped Libya since longtime dictator Moammar Gadhafi was toppled in a 2011 civil war has allowed al-Qaida groups to establish themselves in the southern Sahara wastelands.
It was from Libya that Belmokhtar's group launched its January 2013 attack on the remote Tigantourine gas complex near In Amenas, Algeria, in which 39 foreign technicians were killed.
He moved to Libya after a French-led military force drove al-Qaida in the Islamic Maghreb, al-Qaida's North African wing, out of the sanctuary the size of France in northern Mali AQIM seized in 2012.
That was the first time the jihadists, heavily armed after the Libya war, had sought to hold and govern a large territory. That attempt failed, but other al-Qaida affiliates in Iraq and Syria are currently seeking to carve out a new Islamic caliphate there.
So the North African jihadists may seek to establish a similar statelet, a move that alarms Europe, which has seen itself vulnerable to jihadist attacks since an Algerian bombing campaign in France during the 1990s, followed by al-Qaida attacks in Madrid and London in 2004-05.
Belmokhtar's a maverick. After the Algerian war, he operated with considerable independence in the Sahara region of southern Algeria, engaged primarily in kidnaps for ransom and smuggling.
Since losing Mali, AQIM emir Abdel-Malik Droukdel has sought to concentrate on regrouping and building new operational networks. But Belmokhtar wants to take the war to the "infidel enemy."
"Belmokhtar and his men have emerged as the most military efficient, most ubiquitous and most threatening movement to regional states and Western interests," Oxford Analytica observed.
"He commands well-trained, highly mobile units, able to circumvent satellite surveillance and patrols on the ground, and can count on supportive contacts in an area comprising northern Mali, northern Niger, southern Algeria and southern Libya."
In December 2012, Belmokhtar broke with Droukdel, based in the mountains of northern Algeria, and formed his own jihadist outfit, the Kataibat al-Mulathameen, or the Masked Brigade. He called for attacks across the region to oppose Western influence.
The high-profile attack on Tigantourine, operated by BP and Norway's Statoil, and a later operation involving suicide bombers against a French-owned uranium mining company in Niger were widely seen as designed to enhance Belmokhtar's claim to be a regional jihadist leader.
In August, he forged a new alliance with the Movement for Unity and Jihad in West Africa, an ally in Mali, to form al-Mourabitoun, which refers to an Islamic state established in the desert 1,000 years ago during the Muslim empire that stretched from Spain to Indonesia.
Counter-insurgency experts see danger in this, largely because of Belmokhtar's vision of himself as a paramount jihadist leader.
"Western analysts should be careful not to underestimate the current or future capabilities of al-Qaida's many branches," terrorism specialist Thomas Jocelyn testified before the U.S. Senate Foreign Relations Committee in November.
"Prior to its takeover of much of Mali, the AQIM threat was widely viewed as a criminal problem ... But the organization and its allies have now demonstrated a much more lethal capability.
"They have proven capable of taking and holding territory in the absence of effective central government control. Given that some of the governments in North Africa have only a tenuous grip on power, AQIM and its allies may have the opportunity to acquire additional territory in the future," Jocelyn observed.