THE GERMAN party Alternative for Germany, or AfD, is anti-immigration, anti-Europe-bailout and very anti-Angela Merkel, the chancellor who was just reelected to a fourth term. Founded only four years ago in protest of European bailouts for Greece and riding the backlash to refugees flooding Germany, the AfD reaped 12.6 percent of the vote Sunday and won a place for the first time in the Bundestag. The party was buoyed by social-media campaigns of the kind Russia has used elsewhere — faceless bots that multiply messages over and over. Once again, the Kremlin's quest to disrupt democracy, divide the West and erode the rules-based liberal international order may have found a toehold.

Germany's election watchers say that Russia probably eschewed the kind of blatant interference that it carried out last year in the U.S. election, but that it did its best to support the AfD. In the final hours of the campaign, online supporters of the AfD began warning their base of possible election fraud, and the online alarms were "driven by anonymous troll accounts and boosted by a Russian-language botnet," according to the Atlantic Council's Digital Forensic Research Lab. Earlier, trolls linked to Russia offered continuous support for the AfD and its anti-immigrant message. Russian state-owned media often provided the party's leaders a platform in the Russian-speaking community in Germany.

[Germany’s election gives the country a reality check]

The AfD's success will force Ms. Merkel to negotiate with two smaller parties to form a governing coalition, effectively narrowing her political options. Ms. Merkel's weakened position is partially due to her refugee stand, but it also reflects a fragmenting political environment in Europe, providing an opening for the AfD and other illiberal parties. President Vladimir Putin of Russia has wasted no time exploiting this. He made little secret of his impatience with Ms. Merkel as she steadfastly defended sanctions in response to Russia's subversion of Ukraine and seizure of Crimea, among other things. Mr. Putin would like nothing better than to generate doubts, fog, cracks and uncertainty around the German pillar of Europe. He relishes infiltrating chaos and mischief into open societies. In this case, supporting the far-right AfD is extraordinarily cynical, given how many millions of Russians died to defeat the Nazi fascists seven decades ago.

A normal U.S. president would have something rather blunt to say about the victory of the AfD and the larger, ominous rise of illiberalism across the continent and the globe. A normal president of either party would speak out against hatemongering and racism, and salute those in Germany who have embraced democracy, rule of law and human rights. And such a president would be leading a discussion in the West about how to combat Russian interference in Western democracies. President Trump rarely raises his voice about these values but is strangely full of empathy for autocrats such as Mr. Putin.

Ms. Merkel's main rival, Martin Schulz of the faltering Social Democrats, called the AfD "the gravediggers of democracy." Maybe that is going too far, but it seems prudent to raise the alarm now that gravediggers are coming for democracy, before they begin to sink their shovels into the earth.