ISIS affiliate Al Wilayat Sinai has claimed responsibility for the crash, which killed 224
ISIS in Sinai is very different from ISIS, the terror group that currently occupies large parts of Iraq and Syria. It is a mostly local group of jihadists that feed off long-standing grievances that the population of the Sinai peninsula has with the Egyptian state.
The group has contact with and has pledged allegiance to ISIS's main group, which has its capital in Raqqa, Syria.
But ISIS in Sinai operates largely autonomously, according to various media reports.
How did the terrorist group emerge in Sinai?
Sinai has long been a region with a lot of jihadist activity -- and the peninsula, with its desert in the north and its mountains in the south, is very difficult to control. Egyptian security forces can only deploy very limited equipment and troops there because the area is supposed to be a demilitarized buffer zone between Egypt and Israel.
Furthermore, the indigenous Bedouin population has been cut off from economic and infrastructure development
. Many Bedouin villages don't even have electricity and running water. While the vast majority of Bedouin tribal leaders are against religious violence and many even combat ISIS, some Bedouins have joined the group and make up parts of its rank and file.
Security in Sinai deteriorated even further after the ousting of Egyptian president Hosni Mubarak in 2011. One of the main jihadist groups to emerge at that time was called Ansar Bait al-Maqdis, or "Champions of the Holy House", a reference to Jerusalem and the group's main goal of battling against Israel. It claimed responsibility for various attacks on Egyptian security forces and several bombings of a main gas pipeline that connects Egypt with Israel and Jordan.
In 2013 Abdel Fattah Sisi took power as president of Egypt and launched a major and very heavy-handed crackdown on jihadist groups in Sinai and other areas.
This also further alienated many in the local population and led to the emergence of the group Wilayat Sinai or "Sinai Province" out of Ansar Bait al-Maqdis
What do we know about the leader of Al Wilayat Sinai?
Its leader is Abu Osama al-Masri. This nom de guerre is a reference to his allegiance to Osama bin Laden, while al-Masri is Arabic for "Egypt" to show that he is Egyptian.
Al-Masri directed further attacks on Egyptian security forces and also on Israel. In 2014 he pledged allegiance to Abu Bakr al Baghdadi, the self-proclaimed caliph of the Islamic State in Iraq and Syria.
The ISIS affiliate in Sinai is believed to operate mostly in the northern part of Sinai near the border with Gaza and Israel. According to reports
it possesses mostly light weapons, but also some shoulder-fired anti-aircraft rockets.
A video published by the group purports to show it taking down an Egyptian military helicopter -- but it is believed that such weapons could not take down a cruising airline. While experts believe that the ISIS affiliate in Sinai is fairly small in number, many say they are one of the most active ISIS affiliates.
If Al Wilayat Sinai did bomb the Russian airliner, it could indicate that the terror group is far more dangerous than many previously believed.