"A Russian citizen who previously completed training at an Islamic State international terrorist organization's militant training facility in the Syrian Arab Republic, with the aim to carry out terrorist activities, was detained [in St. Petersburg]," the statement said.
According to the FSB, over 2,900 Russian citizens have been identified as suspected of having links to international terrorist organizations in Syria and Iraq. As many as 198 of them have been killed during hostilities outside Russia, while another 214 returned to Russia and were "taken under tight control of the law enforcement agencies."
Daesh is a designated terrorist group that has captured large areas of land in Syria and Iraq, where it proclaimed a caliphate. The terror group is outlawed in Russia, the United States and in several other countries.