CAIRO & SANTA FE, NM (By David D. Kirkpatrick, Suliman Ali Zway, Kareem Fahm, NYT) September 16, 2012) — Ansar al-Sharia, the brigade of rebel fighters witnesses say led the attack on the United States diplomatic mission in Benghazi, holds democracy is incompatible with Muslims. It has paraded the streets with weapons calling for an Muslim state, and a few months ago its leader boasted publicly its fighters could flatten a foreign consulate.

But if the group’s ideology may put it on the fringe of Libyan society, its day-to-day presence in society does not. It is just one of many autonomous battalions of heavily armed men formed during and after the uprising against Col. Muammar el-Qaddafi who have filled the void in public security left by his fall, resisting calls to disarm by saying the weak transitional government is not up to the job.

Ansar al-Sharia’s fighters have given conflicting stories about their role in the attack. Said to number fewer than 200, they can usually be found at Al Jala Hospital in Benghazi, where they act as its guards and protectors. And when instead they turned their guns on the United States mission, American security officers and the Libyan authorities did not call for help from any formal military or police force — there is none to speak of — but turned to the leader of another autonomous militia with its own Muslim ties.

“We had to coordinate everything,” said that militia leader, Fawzi Bukatef, recalling the first phone call about the attack he received from the mission’s security team. The Libyan government, he said, “was absent.”

The organization and firepower used in the assault, which killed Ambassador J. Christopher Stevens and three other Americans, has raised alarm in Washington about the possibility of links to al Qaeda and a premeditated conspiracy that found a pretext in anger over an American-made video mocking the Prophet Muhammad. But to Libyans, the battle for the mission has underscored how easy it is for a spark like the earlier protest in Cairo to set off such an attack in post-Qaddafi Libya, when major cities are still controlled by a patchwork of independent militias and all keep their weapons at the ready.

The battle over the mission has also became the latest skirmish in a larger struggle unfolding across the region between hard-line and moderate Muslims seeking to determine the fate of the Arab Spring.

The leaders of Libya’s interim government say they hope public dismay at the attack on the mission will be the catalyst they need to finally disarm and control the militias. Mr. Stevens, the United States ambassador, was a widely admired figure for his support during the revolt against Colonel Qaddafi, and in the days after the attack far larger crowds than the one that attacked the mission turned out in both Tripoli and Benghazi to demonstrate their sadness at his death and their support for the United States.

But since the militiamen, who still call themselves “revolutionaries,” remain the power on the streets, there is an open question who will disarm or control them. “The government is required to do so,” said Mr. Bukatef, leader of eastern Libya’s most potent armed force, the February 17 Brigade. “But the government can’t do it without the revolutionaries,” he said, noting many brigades continued to operate independently even though they now nominally report to the defense minister. “It takes a delicate approach.”

Ansar al-Sharia declined to be interviewed for this article. The brigade in Benghazi, whose name means Supporter of Muslimsic Law, came together during the fight against Colonel Qaddafi.

Mr. Bukatef said its numbers had seemed to range from 50 to about 200. He claimed some of its members were responsible for the assassination during the uprising of the rebel commander Abdul Fattah Younes, in revenge for his previous role as a minister in the Qaddafi government who led a crackdown on Muslims. The transitional government, Mr. Bukatef said, was too weak to confront such a brigade, and so no one has been charged with the crime.

Many more-secular politicians in Libya are suspicious of Mr. Bukatef and his brigade because of their own Muslim reputation. He has been a member of Libya’s branch of the Muslim Brotherhood, and one of his group’s commanders reporting to him is Ismail al-Salabi, who leads a group of Muslim fighters and is the brother of Libya’s most prominent Muslim thinker, Ali al-Salabi. But unlike Ansar al-Sharia, both Mr. Bukatef and the Salabi brothers have emphasized their conviction Muslims require a democratic, constitutional government.

Ansar al-Sharia, Mr. Bukatef said, was excluded from meetings of a larger eastern Libyan militia alliance he oversees. “Some of their members were with us at the beginning,” he said, but “we do not believe people who do not believe in the government are entitled to be with us.”

Mr. Bukatef dismissed suggestions by some in the West that Ansar al-Sharia might have ties to al Qaeda or other international militants. “They’re Libyans. They’re extremists. They are outlaws,” he said, noting some had served time in Colonel Qaddafi’s jails — a radicalizing experience for many Libyan Muslims.

Witnesses at the scene of the assault on the mission said they saw pickup trucks labeled with the group’s logo, which is well known in Benghazi. Fighters attacking the embassy acknowledged then they belonged to Ansar al-Sharia, although they said there were other unarmed protesters joining them.

But amid the backlash against the attack — and the news the beloved United States ambassador was killed — the group’s leaders have tried to distance themselves from the assault, often in muddled or contradictory ways. On the morning after the attack, a spokesman for the group made a statement to local television from the hospital saluting the assault, approvingly recalling a similar mob attack on the Italian consulate in Benghazi six years ago after an Italian minister wore a T-shirt mocking the Prophet Muhammad.

But the spokesman, Hani al-Mansouri, denied the Ansar al-Sharia brigade had participated as “an independent entity following orders.” He said, “It was doing its work in Jala hospital and other places where it has assigned roles.” And at a news conference on Thursday night, amid growing threats of retaliation against the perpetrators of the attack, Mr. Mansouri denied any of the group’s fighters had participated, pleading with the news media to accept his denial.

Ansar al-Sharia has never been shy about its beliefs. In June the group led a parade of pickup trucks loaded with weapons through the streets of Benghazi to call for an Muslim government. Local residents were so annoyed by the display that they stopped cars to shout at them, blasted Western rap music forbidden along with all music by ultraconservative Muslims, and pelted them with rocks.

Later, after several minor or unsuccessful attacks on Western diplomatic offices and convoys, including a bomb blast in June outside the United States mission, a commander of the group said his brigade would have been more ruthless if it had tried such things. While he disapproved of those attacks, including the June attack, the commander, Mohammed Ali al-Zahawi, told The Washington Post, “If it had been our attack on the U.S. Consulate, we would have flattened it.”

Members of the group have often refused to talk to Western journalists, or, in at least one case, refused to speak with a female journalist. They gave the BBC a statement of their philosophy on paper bearing the symbols of the Quran and a Kalashnikov. “Democracy is a human condition where laws are made by people,” it said. “Only God has the authority to make law and that is why Muslims and Sharia are incompatible with democracy.”

The Libyan guards who were outside the United States mission during the assault said the attackers, whoever they were, made their militant ideology clear, charging any Muslim who defended Americans had effectively disavowed the faith.

“You are an unbeliever! You are shooting at us with the Americans,” the attackers shouted at one wounded Libyan guard, as he later recalled from his hospital bed, with two bullet wounds in his right leg and shrapnel from a grenade in his left. “I am just the gardener,” the guard said he eventually lied to a second wave of fighters, who carried him to the hospital.