Russian media outlets report that a special large-scale operation carried out by security forces in Moscow and Moscow oblast on Wednesday has led to the arrest of than 25 suspected extremists and terrorism supporters.

Citing a source in the law enforcement authorities, TASS news agency reports the operation was carried out by officers the Federal Security Service together with the Interior Ministry's Anti-Extremism Center and Special Forces.

According to the preliminary data, 25 suspected extremists and terrorism supporters were detained, RIA Novosti reports.

The suspects are believed to be part of a “Wahhabi Underground” in the Moscow region. 

Wahhabism, or Wahhabi mission, is a religious movement or branch of Sunni Islam. It has been variously described as “ultraconservative” and “fundamentalist” movement" to restore “pure monotheistic worship” (tawhid) by advocates and as a distortion of Islam by its opponents.  The term Wahhabi(ism) is often used polemically and adherents commonly reject its use, preferring to be called Salafi or muwahhid.  Wahhabism is named after an eighteenth-century preacher and scholar, Muhammad ibn Abd al-Wahhab (1703–1792).

Many Sunni and Shia Muslims disagree with the Wahhabi movement.  Ulema, including Al-Azhar scholars, regularly denounce Wahhabism in terms such as “Satanic faith.”  Wahhabism has been accused of being “a source of global terrorism” inspiring the ideology of the Islamic State of Iraq and the Levant (ISIL), and for causing disunity in Muslim communities.  It has also been criticized for the destruction of historic mazars, mausoleums, and other Muslim and non-Muslim buildings and artifacts.