Russia has flown drones into Poland and Romania, sent fighter jets into Estonian airspace, buzzed a German Navy frigate in the Baltic Sea and backed an aggressive shadow campaign to sway this weekend’s election in Moldova.

And that’s just in the past three weeks.

The frenzy of Russian action has prompted alarm in European capitals, where officials are worried that Moscow is stepping up its antagonism of Europe, as U.S. resolve to counter Russia recedes under President Trump.

The European jitters extended to Scandinavia this week. Airports in Denmark and Norway shut down because of unexplained drone activity. Denmark’s prime minister said she couldn’t rule out Russia as the culprit. The Kremlin denied involvement and dismissed European concerns about the other recent episodes as “exalted hysteria.”

But perhaps no country in Europe, apart from Ukraine, is feeling the specter of Russian power at the moment more acutely than Moldova.

A parliamentary election there on Sunday could decide whether Moldova, a nation of 2.4 million and a former Soviet republic, continues its path to the European Union under President Maia Sandu or slips back into Moscow’s orbit. Russia has taken aim at Ms. Sandu’s pro-Europe party, unleashing a barrage of influence operations to undermine her government that has intensified with the approach of the vote.