Six things about little-known Al-Qaeda cell Khorasan

US forces took advantage of the air strikes in Syria against the Islamic State in Iraq and Syria (ISIS) to try to simultaneously wipe out the leadership of an Al-Qaeda cell which was allegedly plotting an attack against the United States or Europe. The US forces conducted eight strikes west of Aleppo on Sept 22, 2014, against the Khorasan, targeting its facilities such as training camps as well as explosives and munitions production base.

Here are six things about the little known group:

1. Who is Khorasan?

The group is made up of battle-hardened Al-Qaeda fighters who have set up a franchise of sorts in the contested provinces of Syria. Their goal is to capitalise on the range of nationalities among their ranks to carry out terrorist attacks on Western targets, including the United States.

They share ISIS' extreme interpretation of Sunni Islam and disdain for differing sects within Islam.

But unlike the ISIS, Khorasan is against brutal attacks against Muslims in Syria and Iraq as they fear such violence would erode support for their goals of waging a wider war against western powers.

2. How big is it?

The exact number of fighters is unknown. Estimates range from a few dozen to upwards of 50 fighters, intelligence experts told ABC News.

Khorasan is closely allied with the Nusra Front, which is Al-Qaeda's designated affiliate in Syria, according to US intelligence officials. The Khorasan operatives are from places like Pakistan, Afghanistan, North Africa and Chechnya who have travelled to Syria on the orders of Al-Qaeda leader Ayman al-Zawahri. The Associated Press reported that al-Zawahri dispatched the group to recruit Western fighters, who have a better chance of escaping scrutiny at airports and could place bombs on planes.

Under the protection of the Nusra front, the group has secured land and buildings in the areas surrounding Aleppo. Details of the US-led air strikes suggested that the group has commandeered a range of compounds, including "training camps, an explosives and munitions production facility, a communication building and command and control facilities", according to the US Central Command.

3. Who's in charge?

Muhsin al-Fadhli, 33, a one-time confidant of Al-Qaeda leader Osama bin Laden, is leader of Khorasan. He is said to be one of few Al-Qaeda members who were told of the Sept 11, 2001 plan before the attacks. The State Department, calling Fadhli a "senior facilitator and financier", posted a US$7-million (S$8.9-million) bounty on him and linked him to attacks on a French oil tanker in 2002 and a string of bombings across Saudi Arabia.

Fadhli's rise through the Al-Qaeda ranks was both meteoric and startling. Born on April 24, 1981, in Kuwait, he ascended so quickly that he knew of the Sept 11 attacks when he was barely 20 and was then tapped for additional responsibilities and terror plots. He eventually connected with some of the most notorious terrorists of the past generation, including Abu Musab al-Zarqawi, leader of Al-Qaeda in Iraq.

"He was the bodyguard and second-in-command for a leader in the Al-Qaeda network and fought for Al-Qaeda in the north of Afghanistan," the United Nations reported. "Al-Fadhli also fought against Russian forces in Chechnya, where he trained in the use of firearms, anticraft guns and explosives. Al-Fadhli was a facilitator connected with the al-Zarqawi groups in Iraq, providing support to fighters there."

He is also known for his fund raising and organisational skills. He had stitched together an "extensive network" of Kuwaiti extremist donors, according to the US State Department.

US officials were not certain if Fadhli had been killed in the air strikes in Syria, but Twitter accounts associated with militant groups said he and another Khorasan leader, Abu Yusef al-Turki, had died in the attacks.

Lawmakers and terrorism experts said that even if al-Fadhli had been killed, it would not necessarily derail the group's ambitions. "Fadhli is certainly one of the most capable of the Al-Qaeda core members," said Republican Adam B. Schiff, who is on the House Intelligence Committee. "His loss would be significant, but as we've seen before, any decapitation is only a short-term gain. The hydra will grow another head."

4. What are they planning?

Several officials said Khorasan had a plan for an attack involving a bomb that could pass undetected through airport security systems, perhaps by lacing non-metallic objects like toothpaste tubes and clothes with explosive material.

Lieutenant-general William Mayville, who is in charge of operations for the Pentagon's Joint Staff, said the group was in the "final stages of plans to execute major attacks" either in Europe or the US, having attempted to recruit Westerners who can enter the target countries more easily. Attorney-general Eric Holder said the concerns about Khorasan were behind a decision last summer to ban uncharged laptop computers and cellphones from some US-bound commercial airliners.

5. Why haven't we heard of Khorasan until now?

The group keeps a low profile, in stark contrast to ISIS fighters who regularly release gruesome footage of beheadings and mass executions over social media. Rather than brandishing blades before the cameras, members of Khorasan have reportedly taken a greater interest in developing attacks that would employ concealed weapons.

6. Could it be a greater threat than ISIS?

To the West, perhaps. ISIS has a far greater number of recruits under its command, upwards of 31,000, according to the latest CIA estimate, but its aspirations so far have been fixed on establishing and expanding a caliphate in the region, wresting territories from Iraq and Syria, and driving out or killing waves of ethnic and religious minorities.

Khorasan, on the other hand, seems to have a more single-minded ambition of attacking the US and other Western nations, according to US officials.

The US had not acknowledged the Khorasan by name until as recently as Sept 18 when the director of National Intelligence James Clapper said: "In terms of threat to the homeland, Khorasan may pose as much of a danger as the Islamic State."

While information about the group's members and goals remains scant, officials have made clear with recent comments, punctuated by the air strikes in Syria, that the Khorasan now constitutes one of the chief concerns of the intelligence community.