By expelling scores of Russians from the United States and 21 other countries, President Trump and allied leaders have imposed the most significant punishment yet on Russia and its leader, Vladimir Putin. It’s a move that is well overdue for Mr. Trump, whose long refusal to criticize Mr. Putin and hesitancy to act against Russia’s malign behavior have raised suspicions that Moscow knows secrets it could use to blackmail the American president.

Monday’s development offers some hope that Mr. Trump may finally be forced to deal with the threat that Mr. Putin poses to the United States and its Western allies.

Put the emphasis there on “hope.” Mr. Trump will have to go even further to push back effectively against Mr. Putin’s mischief, which runs the gamut from interference in the elections in America and other Western democracies to propelling the wars in Ukraine and Syria.

The expulsion orders retaliate specifically for the poisoning of a former Russian spy, Sergei Skripal, and his daughter in Britain, for which the Kremlin has been blamed. On the American side, it includes 12 people identified as Russian intelligence officers at the United Nations in New York and 48 at the Russian Embassy in Washington. Also, the Russian consulate in Seattle will be closed because of concerns that Russians were spying on a nearby submarine base and Boeing manufacturing facilities.