The amendments to Russia's penal code envisioning prison terms for Russian mercenaries came into effect on Thursday. Russian citizens participating in armed conflicts abroad face up to six years in prison, according to the amendment passed by the State Duma lower house of the Russian parliament on October 26, 2013. Russian secret services said they had initiated the bill after an increasing incidence of Russian citizens' trips to Syria, who apparently planned to take part in the Syrian war. The mercenaries were mostly natives of the North Caucasus. In late September, First Deputy Director of the Federal Security Service Sergei Smirnov said that 300 to 400 Russians had sided with the Syrian opposition to fight government troops. Smirnov said they had been recruited in Russia, noting that the Russian legislation was vague on stopping mercenaries. A law-enforcement source told Tass that law-enforcers could easily track those leaving the country in order to participate in the Syrian war. "A majority of militants and mercenaries from Russia enter Syria from Turkey. They travel to Turkey as tourists. Imagine several people from a poor Dagestan village simultaneously buying tours to Turkey. Of course, police get suspicious," the source said. Another amendment envisions five to ten years in prison for training in a terrorist camp and up to ten years for gaining practical knowledge to handle weapons, explosives and poisonous substances.