Alexei Navalny has now served more than six months in prison on a charge intended solely to silence Russian President Vladimir Putin’s most outspoken and prominent opponent, and Mr. Navalny’s organization has been gutted by the Russian authorities. With a steady tightening of the screws, Mr. Putin is decimating what is left of Russia’s civil society.

Mr. Putin’s security services attempted to poison Mr. Navalny a year ago, and he spent five months recovering in Germany. When he courageously returned to Russia on Jan. 17, he was charged, absurdly, with violating the terms of a suspended sentence in a six-year-old case that the European Court of Human Rights had called “arbitrary.” A Russian court nonetheless sent Mr. Navalny to prison in February for 32 months.

As thousands attended rallies to support Mr. Navalny, the authorities arrested his close ally Lyubov Sobol, among other well-known activists, on charges of breaking pandemic regulations. The public demonstrations, including one in early February, were met with force, and nearly 10,000 people were detained across the country. Russian authorities launched more than 90 criminal cases against protesters; nearly two dozen of these defendants were sentenced to jail time.

In May, legislation was introduced to outlaw anyone designated an “extremist” by the government from running for election. The bill was rushed through parliament and signed by Mr. Putin on June 4. Five days later, a Moscow court ruled that Mr. Navalny’s organizations are “extremist.” This effectively barred anyone affiliated with Mr. Navalny from running for office in September’s elections. Mr. Navalny’s backers had succeeded in a political strategy known as “smart voting,” advancing select candidates to defeat those backed by the Kremlin. Now his network of offices is closed. As the U.S. State Department aptly put it, “With this action, Russia has effectively criminalized one of the country’s few remaining independent political movements.”

On Aug. 3, Ms. Sobol was sentenced to parole-like restrictions for a year and a half, stemming from her January arrest on the pandemic charge, which she correctly called nonsense. On Aug. 7, she left Russia.

All of Russian civil society is under pressure. News organizations are regularly being labeled “foreign agents” and required to issue a disclaimer on every article and broadcast. Those singled out include Meduza; Radio Free Europe/Radio Liberty; a business news site, VTimes; and an investigative news site, the Insider. Authorities raided the home of the Insider's editor in chief, Roman Dobrokhotov, who has often partnered with Bellingcat, the open-source organization that helped expose the actions of Russia’s security services, including the attack on Mr. Navalny. The investigative site Proekt was labeled an “undesirable organization” and banned.

Russia used a chemical weapon to poison Mr. Navalny. President Biden is overdue in imposing mandatory sanctions for it. When Mr. Biden met with Mr. Putin in June, the American president raised Mr. Navalny’s persecution and vowed to keep up the pressure, because “that’s what we are, that’s who we are.” Mr. Biden pledged to “stand up for the universal and fundamental freedoms that all men and women have, in our view.” Yet two months later, Mr. Putin’s war on civil society grinds on.