British authorities on Wednesday indicted two men for the March chemical-weapons attack on a former Russian double agent on British soil. The new details add to the evidence that Vladimir Putin’s regime is responsible, but its reckless methods are the real stunner. Police and prosecutors allege the men they identify as Alexander Petrov and Ruslan Boshirov—almost certainly pseudonyms—arrived at London’s Gatwick airport on Friday, March 2, smuggling the weapons-grade nerve agent Novichok in a small counterfeit perfume bottle. They ferried the chemical on suburban trains and the Tube through central London to a hotel, where nonfatal quantities of Novichok were...