At the consulate where four Americans died security consisted of one U.S. regional security officer and a local militia. Ambassador Chris Stevens often had little or no personal security detail. NBC's Lisa Myers reports.

For years, the United States has been concerned about al-Qaida's recruiting along a coastal highway in eastern Libya. The stretch of highway, extending from Derna in the east, through Benghazi — the scene of the attack on a U.S. consulate that killed U.S. Ambassador Christopher Stevens and three other Americans last week — to Ajdabiya in the southwest, has earned a reputation as a breeding ground not just for Libya's indigenous Islamists, but also for al-Qaida central on the Afghan-Pakistan border.

Robert Windrem is senior investigative producer for NBC News. Robert Windrem is senior investigative producer for NBC News.

Counterterrorism experts inside and outside the U.S. government argue that it is not an exaggeration to suggest that the region around Benghazi has become a crucial wellspring for al-Qaida that rivals even its historic breeding ground — Saudi Arabia.

The area has produced many members of the terrorist organization's leadership, supplanting or at least complementing Saudi and Egyptian roles.

Following Tuesday's deadly attack, U.S. and Libyan officials are trying to determine what role homegrown radical Islamists played in the violence. Many U.S. and Libyan officials now believe the attack was planned, possibly by Libyan jihadists who have returned to their old stomping grounds after having traveled the Islamic world in recent years.

The Libya connection "Several Libyans have risen in the ranks of al-Qaida, not because they were Libyan, but because they had unique skills and long-term relationships with the senior leadership that go back to the pre-9/11 days in Afghanistan," a U.S. official says. Here are some of those Libyan fighters who have assumed key positions in the al-Qaida hierarchy in recent years, according to U.S. officials: - Atiyah Abd Al Rahman, Osama bin Laden's "chief of staff" at the time of his killing in May 2011. Rahman was bin Laden's main contact with al-Qaida commanders, materials found in bin Laden's Pakistan compound showed. Correspondence between the two men grabbed by the Navy SEALs from the compound provided the most revealing details of his plans. After his mentor's death, Rahman was elevated to the No. 2 position in the organization, replacing Ayman al-Zawahiri when he succeeded bin Laden. Three and a half months after bin Laden's death, Rahman was killed in a drone strike. - Abu Yahya al-Libi, born Mohamed Hassan Qaid, was al-Qaida's second-in-command until he was killed, having succeeded Rahman. Although there is little information about his early years, al-Libi is believed to have lived in eastern Libya. He fought in Afghanistan and studied Islam in Mauritania, in North Africa, and arrived in Iraq in 2002 to join the fight against the U.S. forces. He was captured but escaped from the U.S. detention facility in Bagram, Iraq, in 2005. His story gave him instant credibility, and he began producing videos and audios. He was killed in a drone attack on Mir Ali in North Waziristan in June. - Abu Faraj al-Libi, born Mustafa al-'Uzayti, was al-Qaida's third in command and the director of its international operations until he was captured by Pakistani forces in May 2005. He is imprisoned at the U.S. naval facility at Guantanamo Bay, Cuba, where he awaits trial on terrorism charges. Pakistani officials have accused him of playing a lead role in planning a failed plot to simultaneously blow up 10 U.S.-bound passenger jets. He was captured while riding a motorbike on May 2, 2005, and subjected to so-called enhanced interrogation techniques. - Abu Laith al-Libi was an al-Qaida field commander and spokesman, rising to director of military operations and the No. 4 position in the terrorist group. An outspoken and charismatic leader, he often appeared in videos and on the Internet until his death in 2008. It was he in July 2002 who revealed that bin Laden was still alive, the first comments about the al-Qaida leader's health after the end of the Afghan conflict. Then, in June 2004, he was shown leading an attack on what appeared to be an Afghan military outpost. He worked with the remnants of the Taliban. U.S. officials called him an expert in guerrilla operations. He was killed in a drone attack on Jan. 29, 2008. Adm. Mike McConnell, the former director of national intelligence, said at the time of al-Libi's death that it was "the most serious blow to the group's top leadership since the December 2005 death of then-external operations chief Hamza Rabia."

"Libya, like many other countries, has areas with a history of extremism that the government is trying to counter," a U.S. counterterrorism official told NBC News on condition of anonymity, referring to the Benghazi region.

'Prolific incubator for local extremists'

Evan Kohlmann, a U.S. Justice Department consultant on al-Qaida and an NBC News analyst, said Benghazi's reputation as a hotbed of Islamic militancy was cemented long ago.

"For more than two decades, a slice of eastern Libya near Benghazi, dominated by conservative bastions like the town of Derna, has served as a prolific incubator for local extremists, a surprising number of whom have surfaced as high-profile foreign combatants in conflicts ranging from Afghanistan, Bosnia, Chechnya, Iraq and now Syria," he said.

"Several of these combatants have taken leading roles in front-line paramilitary organizations, including al-Qaida," Kohlmann added.

Crowds of angry protesters showed up in Kabul, Afghanistan and Jakarta, Indonesia. The violent uprising followed a deadly weekend marking the deaths of eight International Security Assistance Force members. NBC's Atia Abawi reports.

An NBC News analysis of known al-Qaida leaders bears that out, indicating that the nearly 300-mile corridor between the desert and the Mediterranean Sea has produced more senior al-Qaida members than anywhere else in the Islamic world over the past seven years.

The attack on the Libyan consulate, as it happened

Among them: al-Qaida's last two seconds-in-command, as well as its international operations director (the No. 3 position in al-Qaida leadership) and its military commander — No. 4 in the hierarchy and a position typically held by some of its more charismatic propagandists. Each became a high-value target for the United States, and their deaths or captures have been trumpeted by U.S. intelligence and counterterrorism agencies.

"Leadership in al-Qaida circles tends to go in waves as colleagues bring with them established friends because of established trust," said Michael E. Leiter, former director of the National Counter Terrorism Center and now an NBC News analyst.

"For the longest time, it was what was colloquially known as the Egyptian Mafia, but gradually this group was decimated by strikes. The Libyans did rise to prominence based on a couple of charismatic leaders and the influx of the Libyan Islamic Fighting Group ranks. And there is undoubtedly a strong current of the most extreme forms of Salafism in some parts of Libya that had served as a breeding ground for such al-Qaida foot soldiers and leaders," Leiter said.

Ambassador Rice: Benghazi attack began spontaneously

The close ties between al-Qaida Central in Pakistan and the Libyans were cemented in 2007 when the Libyan Islamic Fighting Group, a radical group formed to overthrow Libyan dictator Moammar Gadhafi, broke apart, leading several leaders to join al-Qaida at the same time others were denouncing the violence of Osama bin Laden's operations.

A December 2007 report (.pdf) on foreign fighters in Iraq, produced by the Countering Terrorism Center at the U.S. Military Academy pointed out the significance of the Libyan recruiting to the rise of al-Qaida in Iraq, the local branch of the broader terror group, during the height of the Iraqi civil war.

Libyan fighters stream into Iraq

Starting in November 2007, the center analyzed nearly 700 records of foreign nationals who entered Iraq from August 2006 to August 2007. The data came from personnel records seized from al-Qaida in Iraq, which had jihadists fill out questionnaires as they arrived in Iraq.

Anti-US protests erupt in Kabul as Western missions tighten security

Of 591 records that included the countries of origin of the fighters, Libya was the second most common after Saudi Arabia — 18.8 percent (112) of the fighters reported that they hailed from Libya. And of that number, a staggering 90 percent came from the Derna-Benghazi-Ajdabiyah corridor.

Libyan President Mohamed Magariaf said foreign elements were involved in the attack on the U.S. Consulate in Benghazi — the first time Libya has officially acknowledged that it wasn't a spontaneous protest. NBC's Ayman Mohyeldin reports.

The most common cities that the fighters called home were Derna, Libya, and Riyadh, Saudi Arabia, with 52 and 51 fighters respectively. Derna, with a population just more than over 80,000 compared to Riyadh's 4.3 million, has far and away the most fighters per-capita in the records.

A Meet the Press panel discusses the role the United States plays in the Middle East.

In fact, one out of every 1,000 residents of the 300-mile corridor from Derna to Ajdabiya wound up in Iraq during that single year.

Darna's importance to the jihadist presence inside Libya was underscored earlier this year when a series of bombings was attributed to a battle for power among rival jihadist groups. There were also rumors that Ayman al-Zawahiri, al-Qaida's leader following the death of bin Laden, had dispatched a commander to Derna.

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Roger Cressey, former deputy director of the National Security Council's Counter Terrorism Division, said the attack on the U.S. Consulate is likely to raise awareness of how important this region has become to al-Qaida.

"Given the presence of al-Qaida-influenced extremists in the area, this corridor will become a priority for U.S. counterterrorism," said Cressey, now an NBC News analyst. "It will join Pakistan, Yemen and Somalia."

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