“Immigration Behind Shortage of Drinking Water in Northern Stockholm,” read one recent headline. “Refugee Minor Raped Host Family’s Daughter; Thought It Was Legal,” read another. “Performed Female Genital Mutilation on Her Children — Given Asylum in Sweden,” read a third.

Russia’s hand in all of this is largely hidden from view. But fingerprints abound.

For instance, one writer for Samhallsnytt, who previously worked for the Sweden Democrats, was recently declined parliamentary press accreditation after the security police determined he had been in contact with Russian intelligence.

Fria Tider is considered not only one of the most extreme sites, but also among the most Kremlin-friendly. It frequently swaps material with the Russian propaganda outlet Sputnik. The site is linked, via domain ownership records, to Granskning Sverige, called the Swedish “troll factory” for its efforts to entrap and embarrass mainstream journalists. Among its frequent targets: journalists who write negatively about Russia.

“We’ve had death threats, spam attacks, emails — this year has been totally crazy,” said Eva Burman, the editor of Eskilstuna-Kuriren, a newspaper that found itself in the cross hairs after criticizing the Russian annexation of Crimea and investigating Granskning Sverige itself.

At the magazine Nya Tider, the editor, Vavra Suk, has traveled to Moscow as an election observer and to Syria, where he produced Kremlin-friendly accounts of the civil war. Nya Tider has published work by Alexander Dugin, an ultranationalist Russian philosopher who has been called “Putin’s Rasputin”; Mr. Suk’s writings for Mr. Dugin’s think tank include one titled “Donald Trump Can Make Europe Great Again.”

Nya Tider’s contributors include Manuel Ochsenreiter, editor of Zuerst!, a German far-right newspaper. Mr. Ochsenreiter — who has appeared regularly on RT, the Kremlin propaganda channel — worked until recently for Markus Frohnmaier, a member of the German Bundestag representing the far-right Alternative for Germany party. Documents leaked to a consortium of European media outlets — documents that Mr. Frohnmaier has called fake — have suggested that Moscow aided his election campaign in order to have an “absolutely controlled MP.”

Mr. Ochsenreiter, for his part, has been implicated in Polish court in the financing of a 2018 firebombing attack on a Hungarian cultural center in Ukraine. The plot, according to testimony from a Polish extremist charged with carrying it out, was designed to pin responsibility on Ukrainian nationalists and stoke ethnic tensions, to Russia’s benefit. Mr. Ochsenreiter has not been charged in Poland, but prosecutors in Berlin said they had begun a preliminary investigation. He has denied involvement.