Senior politicians appear increasingly convinced that an organization affiliated with the Islamic State militant group (ISIS) played some role in the downing of a Russian passenger plane in Egypt.
Who are the militants, and how much influence do they have in Egypt?
British Foreign Secretary Philip Hammond said on Thursday that there was a "significant possibility" that ISIS militants in Sinai were behind the tragedy, which resulted in the death of all 224 people on board. U.S. intelligence also suggested that the crash may have been caused by a bomb on board.
The branch of ISIS in Sinai—known as the Sinai Province, or Wilayat Sinai—immediately claimed responsibility for the crash. It has been launching sustained attacks against Egyptian army and police targets throughout 2015.
Newsweek spoke to experts to consider how a group that joined the ISIS brand only 12 months ago has now become one of its most active and dangerous affiliates.
What is the Sinai Province?
The Sinai Province is the successor to a previous militant organization known as Ansar Beit al-Maqdis, or Ansar Jerusalem, a name that translates as "Supporters of the Holy House/Jerusalem."
According to Stanford University, Ansar Beit al-Maqdis formed in Egypt and the Gaza Strip in 2011 following the ousting of former President Hosni Mubarak. It was declared a terrorist organization by the U.S. State Department in October 2014 following attacks in Northern Sinai that killed 33 security personnel.
In November 2014, the group pledged allegiance to the ISIS central command in Syria and changed its name to the Sinai Province.
The group has between 1,000 and 2,000 fighters, Michael Horowitz, geopolitical analyst at security consultancy the Levantine Group, tells Newsweek. The BBC estimates it to have around 1,000-1,500 active members.
What is the group's connection to ISIS?
Before the 2014 pledge of allegiance, leaders of the then-Ansar Beit al-Maqdis traveled to ISIS headquarters in Syria to coordinate the groups' activities, according to Horowitz. Since then, the militants have ramped up attacks on Egyptian soil, carrying out more than 700 attacks—mostly on Egyptian army and police targets—in the first half of 2015.
The high level of coordination and sophistication involved in these attacks, which included booby-trapping roads, led to reports that the group must have been receiving intelligence and support from the central command of ISIS.
According to Horowitz, the propaganda campaign surrounding the Russian jet crash is proof of the close links between the Sinai Province and ISIS.
First, a statement was put out by the Sinai Province, immediately claiming responsibility for the crash. The claim was then released in multiple languages—including English, Spanish and Turkish—before it was broadcast by ISIS's official Al-Bayan radio station in Iraq.
"It really shows that there is a strong connection between the Islamic State in Sinai and the Islamic State leadership in Iraq and Syria," Horowitz says. "It was not just a small group in Sinai claiming it but it was really a coordinated media effort."
What are the Sinai Province's goals?
Currently, the militants do not control any territory in Egypt, according to Horowitz. Prior to the 2014 pledge of allegiance, Ansar Beit al-Maqdis launched sporadic attacks in the Sinai peninsula while also targeting Israeli troops and positions. Since the group's closer affiliation with ISIS, Horowitz says it has focused on gaining territory and limited its scope to the Sinai towns of Rafah, Sheikh Zuweid and El-Arish.
He adds that the group has expressed an interest in ending the Egyptian blockade of Gaza, which he says would represent a huge "symbolic victory" for ISIS. In July, the Israeli military bolstered security along the southern border with Egypt, fearing that the Sinai Province may launch an attempt to take control of the Gaza Strip.
ISIS has also said it intends to overthrow Hamas, the militant Islamist group currently controlling Gaza.
The Sinai Province has also employed similar methods to ISIS in Syria and Iraq. In August, the Sinai Province claimed to have kidnapped and beheaded Tomislav Salopek, a Croatian engineer working in Egypt.
What is Egypt doing about the Sinai Province?
Since July 2013, the Egyptian army has been demolishing buildings and forcibly evicting residents along the border with the Gaza Strip in a bid to stop what it says is coordination between militants in Sinai and Gaza. In September, Operation "Right of the Martyr" was launched as the army and Egyptian police redoubled efforts to clear the Sinai region of militants, and security forces killed 55 militants in one operation.
According to H.A. Hellyer, associate fellow at the Royal United Services Institute, a U.K. defense think tank, the ongoing presence of the Sinai Province—which he says is spreading to Egypt's Western desert and has also claimed attacks in the capital Cairo—shows that Islamist militancy is alive and well in Egypt.
"The Egyptian government insists that everything is under control, but ISIS still exists in Sinai after a high-level campaign against it for two years," Hellyer says. "It's not a pretty picture."
Was the Sinai Province involved in the Russian plane crash?
A number of possible causes of the crash—including a technical fault with the plane or external impact—have already been ruled out by investigators. The idea that militants may have planted or organized the planting of a bomb on the plane remains one of the few theories that has not been discounted, and British Prime Minister David Cameron said on Thursday that an explosive device planted on the plane was "more likely than not."
Horowitz says a number of factors mean that the Sinai Province's claim of responsibility must be considered credible.
The timing of the crash is significant, according to Horowitz: It came almost exactly a year after the group's pledge of allegiance and followed Russia's launching of airstrikes against ISIS targets in Syria, to which the militants responded by calling for a "holy war" against Russians and Americans.
He adds that ISIS has built its reputation on making credible claims for attacks and that it would not risk the damage to its reputation of making unfounded claims.
Even if the Sinai Province's involvement in the attack is disproved, Hellyer believes that the exposure it has gained in the meantime will serve its purposes.
"All this attention on Wilayat Sinai [Sinai Province] would give it a level of prominence it's not had before in the international extremist universe," Hellyer says. "They've controlled the narrative [of the crash]—that's a victory in and of itself."