MAIDUGURI, Nigeria, March 7 (UPI) -- Boko Haram, which has since 2009 waged war seeking an Islamic government in Nigeria, officially pledged allegiance to the Islamic State on Saturday, making it the latest terrorist organization to align itself with the group.
The audio statement was made by Boko Haram's leader and posted to Twitter but has not been verified.
Earlier this month a video posted to Boko Haram's Twitter account depicted the beheading of two accused spies, leading experts to speculate the groups might be working together. Since last summer IS has infamously used video of beheadings as a terror tactic.
The pledge is the latest in a series of declarations made by extremists worldwide since IS captured large swaths of territory in Iraq and Syria last year, leading IS leader Abu Bakr al-Baghdadi to declare a caliphate in June.
In July 2014 the leader of Filipino terrorist group Abu Sayyaf pledged allegiance to IS in a video posted to Facebook.
In Sept. 2014 Algeria's Jund al-Khilafah, or "Soldiers of the Caliphate in Algeria," split from al-Qaida's North Africa branch and declared allegiance to IS.
In Oct. 2014 prominent leaders of the Pakistani Taliban, otherwise known as Tehreek-e-Taliban Pakistan, or TTP, gave oaths of allegiance to IS, with TTP spokesman Shahidullah Shahid saying, "From today, I accept Abu Bakr al-Baghdadi as my caliph and will accept every directive of his and will fight for him whatsoever the situation."
Libya's Majlis Shura Shabab al-Islam, or "The Islamic Youth Shura Council," which had formed in April 2014, declared allegiance to IS and seized the city of Derna on Libya's northeastern Mediterranean coast in November, saying it was now a part of the IS caliphate. The affiliate last month posted a video of militants beheading Coptic Christians from neighboring Egypt.
On Nov. 10, Egyptian Islamist group Ansar Beit al-Maqdis, based in the Sinai Peninsula, pledged loyalty to al-Baghdadi in an audio message on Twitter.
"We give you good news by announcing the expansion of the Islamic State to new lands ... the lands of Al Haramayn [Saudi Arabia], Yemen, Egypt, Libya and Algeria," al-Baghdadi announced at the time.
On Nov. 21 Omar al-Chechen, leader of a Chechen militant group known as Jaish al-Muhajireen wa Ansar, or "Army of the Emigrants and Helpers," declared allegiance to al-Baghdadi in an online statement.
"ISIS is a brand name," Samer Shehata, an associate professor of Middle Eastern politics at the University of Oklahoma, told NPR in November, using an alternate acronym for the Islamic State. "It has widespread recognition, and in the eyes of many adherents, it's successful."
While IS used to be an affiliate of al-Qaida, the two groups have grown into adversaries. In Dec. 2014 Harith bin Ghazi al-Nadhari, a senior sharia official with al-Qaida in the Arabian Peninsula, released a video rebuking al-Baghdadi's claim that the IS caliphate extended to Yemen, where AQAP is based.
Al-Qaida also disputes al-Baghdadi's claim to be the caliph, a position for which the extremist group -- including al-Qaida leader Ayman al-Zawahiri -- recognizes Taliban leader Mullah Omar. Al-Qaida's Syrian affiliate, the Nusra Front, has since engaged IS forces in battle.