Czech President Milos Zeman reacts to his reeelection Saturday in Prague. (Stringer/Reuters)

MILOS ZEMAN, the president of the Czech Republic, speaks and acts as if he were a pure Russian agent. Virtually alone among senior Western politicians, he defends the seizure and annexation of Crimea by the regime of Vladi­mir Putin, denies the presence of Russian forces in eastern Ukraine and calls for the lifting of all sanctions on the regime. Following his reelection Saturday, he reiterated his proposal that Czechs vote in a referendum on whether to remain in NATO and the European Union — the fracturing of which is the Kremlin's most treasured goal.

It therefore shouldn't be surprising that Mr. Zeman's narrow reelection was aided in part by significant spending of unknown origin, and by a vicious online disinformation campaign directed against his opponent. Jiri Drahos, an honorable scientist who campaigned against Mr. Zeman on a platform of reaffirming ties to the West, told The Post it was "logical" to suppose that the assault could be traced to "the Russian secret service and related organizations" — and he is right.

The outcome of the Czech election is a setback for the West and its supporters in the country, but as important, it is evidence that the Putin regime has not restrained its efforts to subvert Western democracies through disinformation and corruption, despite increasing exposure of the operations and sanctions imposed following the 2016 U.S. election. The Czech case is one more warning that Moscow can be expected to target the upcoming U.S. midterms — and that, to date, the Trump administration has done next to nothing to defend the American electoral system.

The attacks on Mr. Drahos will be painfully familiar to candidates across Europe who have been subject to previous Russian campaigns, not to mention Hillary Clinton. According to the Prague-based European Values Think-Tank , in the closing days of the campaign, the mild-mannered former head of the Czech Academy of Sciences was the subject of a barrage of false stories spread by websites, emails and social media postings. Among other things, he was accused of being an agent of the former communist secret police, a pedophile, a member of a secret globalist society and an advocate of mass Muslim immigration. He is manifestly none of those things.

Mr. Zeman, who prides himself on his use of foul language and heavy consumption of tobacco and alcohol, meanwhile benefited from a billboard and newspaper advertising campaign sponsored by unidentified "friends." The message was the same that the president has used in recent years to build a base of support among older people and those in rural areas: xenophobia directed at Muslims and other potential immigrants.

Though the Czech Republic has accepted only 12 of the 2,600 asylum seekers it was assigned by the E.U., Mr. Zeman warns of a Muslim "invasion" that could trigger a "super-Holocaust." He has called for the "liquidation" of journalists who criticize him and spoken of women in crude, sexist terms. He proudly calls himself "the Czech Trump." That he was reelected speaks to the broad attraction of crude ethno-populism in countries across the West. That he likely had help from Moscow should be of concern to Americans of both parties seeking office this November.