Egyptian soldiers keep guard during a military operation in the Egyptian city of Rafah on Oct. 30. Reuters

Ansar Beit al-Maqdis made headlines recently when it publicly pledged allegiance to the Islamic State group in a nine-minute audio speech posted to Twitter. Here's a distilled rundown of the basic facts you need to know about the Egyptian extremist group.

Who Are They?

Ansar Beit al-Maqdis, sometimes called Ansar Jerusalem, is based in the Sinai Peninsula. The United States and United Kingdom designated it as a terrorist group in April. Ansar Beit al-Maqdis is Egypt's most active armed group, according to Al-Jazeera, and its number of supporters could reach 2,000. "They are just different names for the same terrorists," interior ministry spokesman Hany Abdel told Agence France-Presse.

What Have They Done?

The jihadist group has claimed responsibility for violent acts dating back to the Egyptian Revolution of 2011, including pipeline bombings, attacks on military intelligence, launching rockets and an assassination. Most recently, Ansar Beit al-Maqdis was thought to have killed 28 soldiers with a car bomb Oct. 24.

In August, Ansar Beit al-Maqdis posted a 30-minute video online showing four Egyptians blindfolded and beheaded, Al Arabiya reported. The video drew attention for its similarity to videos sent out by the Islamic State group.

Why Do We Care Now?

On Sunday, Ansar Beit al-Maqdis announced its loyalty to the Islamic State group in a message posted to Twitter. The organization had spoken in favor of the Islamic State group before but never cemented its stance. The speaker in the audio clip encouraged Muslim listeners to do the same: "Your unity is strength, and your division is weakness.... Determine your fate, unite among yourself, and support your State."

This was concerning to international officials because it meant the Islamic State group's influence was spreading. On top of that, Al-Monitor reported that Egypt's government could lose control of the Sinai Peninsula, which would allow terrorist groups to do essentially whatever they want in the area.

The Twitter message specifically mentioned Abu Bakr al-Baghdadi, the leader of the Islamic State group thought to be wounded by a recent airstrike. God chose al-Baghdadi to create a new regime, the Ansar Beit al-Maqdis speaker said. "We have no alternative but to declare our pledge of allegiance to the caliph ... to listen and obey him," the speaker said, and Egyptians, in the meantime, should rebel against "the tyrant," President Abdel Fattah el-Sisi, the Associated Press reported. "We will continue to fight the army until the day of judgment," the speaker said.