Russia's Federal Security Service (FSB) has arrested seven Moscow residents said to be linked to a pro-Kyiv militia accused of attacking Russia's border regions, state news agencies reported on Friday.The arrests come days after Russian President Vladimir Putin ordered the FSB to wage an unrelenting crackdown on volunteer units fighting on the side of Ukraine, whom he called "scum" traitors."The seven detained residents of Moscow maintained contacts with the Russian Volunteer Corps, acting as part of the Ukrainian army," the FSB was quoted as saying by state media, referring to one of the militia groups.According to the FSB, those detained had "discussed ways of carrying out violent acts against members of law enforcement agencies, servicemen and foreigners."A video published by state news agencies showed FSB officers bursting into an apartment and detaining one of the suspects.The militias, which say they are made up of Russian citizens who oppose Moscow's full-scale invasion of Ukraine, claim to have been behind a string of brazen incursions into regions in western Russia.After last week's raids, which targeted the Kursk and Belgorod regions, Putin ordered the FSB to punish the fighters "without a statute of limitation."