Mandatory Credit: Photo by STEPHEN BRASHEAR/EPA-EFE/REX/Shutterstock (9478433h) The entrance to the Russian Consulate in Seattle, Washington, USA, is pictured on 26 March 2018. Reports on 26 March 2018 state the US will expel 60 Russian diplomats as a reaction to the poisoning of Russian former spy Sergei Skripal and his daughter Yulia in Britain. USA to expell 60 Russian diplomats in wake of poisoning of Russian former spy Sergei Skripal in Britain, Seattle - 26 Mar 2018 (Stephen Brashear/Epa-Efe/Rex/Shutterstock/Stephen Brashear/Epa-Efe/Rex/Shutterstock)

THE UNITED STATES joined with 19 other countries Monday in what was described as the largest-ever collective expulsion of Russian intelligence officers. The Trump administration’s contribution was the biggest: Sixty officials with diplomatic status were ordered out of the country, and the Russian consulate in Seattle was closed. The expulsions were a needed response to the nerve-agent attack on a former spy and his daughter inside Britain — the latest audacious act of aggression by the regime of Vladi­mir Putin. But because they do not touch Mr. Putin’s real power base, he will probably shrug them off.

Russia’s espionage apparatus in the West is huge, as the scale of the expulsions indicates. Including an earlier action by Britain, some 135 Russian officials have been ordered out of 21 countries in response to the March 4 attack on Sergei Skripal and his adult daughter, Yulia. This could deal a temporary blow to Russian intelligence services.

However, Russia’s malign operations in the West extend far beyond the agents it dispatches under diplomatic cover. It has an army of hackers and trolls operating online, many of whom have been busy attempting to sow confusion about responsibility for the use of the nerve agent. Mr. Putin depends on a network of government ministers and business owners to fund these operations and others — like the paramilitary force that recently attacked U.S. troops in Syria. That is the real foundation of his regime, and so far it has barely been touched.

Both the British government and the Trump administration have potentially potent leverage. Many Russian oligarchs and some senior government officials have millions invested in the London property market. The government of Theresa May has legal authorities it could use to target some of those assets, but it has not yet done so. Similarly, Congress passed legislation last year mandating the creation of a list of oligarchs and officials close to Mr. Putin who could be subject to asset freezes and visa bans. The administration grudgingly produced the list but has yet to act, apart from the recent designation of a handful of officials and Internet hackers, most of whom were already under indictment or sanction.

Both governments, as well as European Union officials, are promising further action, and we hope that it is forthcoming. But there is reason for concern, given the substantial support Mr. Putin continues to enjoy from several E.U. governments and the curious behavior of Mr. Trump, who seemingly cannot bring himself to criticize the Russian leader. When Mr. Trump called Mr. Putin last week, he ignored the advice of his advisers and did not mention the nerve-gas attack. Instead he promised to meet Mr. Putin soon and embraced his priority of arms-control negotiations. Then he took to Twitter to argue, again, that “getting along with Russia (and others) is a good thing.”

Getting along would be good, on the right terms. But it’s not feasible as long as the Kremlin is dedicated to disrupting Western governments and elections, subjugating neighbors such as Ukraine, and murdering its opponents in Western cities using banned chemical agents. Mr. Putin must be deterred. Expelling a few dozen of his spies is a step, but it’s not likely to suffice.