Russia’s Federal Security Service has killed 14 terrorists believed to be part of the Islamic State group in the North Caucasus region of Russia, according to details released by Russia's National Anti-Terrorism Committee. Security forces killed eight Sunday in the republic of Ingushetia -- west of Chechnya -- while six were killed Monday in Nalchik, the capital of Kabardino-Balkaria, according to a Moscow Times reports.

Russian authorities have struggled to contain Islamic extremism that has gripped the North Caucasus region, an area that is primarily a mix of Muslim republics in the south of Russia. The Islamic State group declared the entire region as part of its caliphate earlier this year.

It was claimed by Russian security forces that those killed on Monday were involved in “terrorist crimes,” including extorting money and killing law enforcement officials. Sunday’s eight deaths included the group’s leader, Adam Tagilov, who had been accused of staging an attack on Grozny -- Chechnya’s capital city -- in 2014. Local reports suggested that 25 had died in that attack.

In Nalchik, another predominately Muslim area in the North Caucasus, authorities said the that six were killed were suspected of aiding terror. 

Fighters from the North Caucasus are popular inside the Islamic State group, also known as ISIS, given the experience that comes with fighting two wars against Russia in the 1980s and 1990s. It's thought that fighters from the North Caucasus region are responsible for a lot of the gains made by ISIS in Iraq and Syria. 

The deaths in Chechnya also cast doubts over Chechen leader Ramzan Kadyrov’s claims that the region has no security issues and is safe.

Kadyrov said at the end of last month that all Chechens fighting with ISIS had returned home, calling them “hooligans,” while also saying that he would love the opportunity to fight against the terror group that has taken over large parts of Syria and Iraq.

Russian officials have estimated that around 2,000 men have left the country to join the group. However, according to the Grand Mufti of Syria, more than 7,000 Russians are fighting alongside the terror group.