Russia’s Federal Security Service (FSB) arrested five Islamic State members on Tuesday; they were apparently plotting a terrorist attack in the Republic of Ingushetia and Moscow.

The Russian intelligence service searched the hideout of the suspects and recovered firearms, homemade explosive devices containing TNT, home-made electric detonators, and various types of ammunition.

That is not the first arrest of IS operatives in Russia. In October, a cell of six was killed in Ingushetia, in the Russian North Caucasus.

IS members were arrested in February; apparently, they were also planning attacks in Moscow and St. Petersburg.

Over 2,500 Russian nationals are estimated to have joined the ranks of IS since 2015. Militants from Russia are thought to be involved in the June 2016 terrorist attack at the Ataturk Airport in Istanbul killing 45 people.

Russia has become a target due to its engagement in the Syrian campaign in support of the President Bashar al-Assad regime. ISIS has also claimed responsibility for the downing of Metrojet Flight 9268 over Egypt’s Sinai Peninsula in October 2015.