For the damage done by Edward Snowden dwarfs the impact of Cold War traitors and defectors. Western agencies now assume that the NSA material is in the hands of Moscow and Beijing, or will get there eventually. Many worthwhile intelligence operations must be shut down or started anew: A serious spy service does not risk lives on the hopeful assumption that the other side will not exploit its blunders.

I accept that a debate is overdue on the collection and warehousing of metadata (details about the location, duration and direction of a phone call, but not its content). If you know who called a suicide-prevention helpline, and from where and when, the contents of the call matter less than the circumstances. The NSA may have deliberately weakened the hardware and software sold by American companies in order to be able secretly to exploit those vulnerabilities. If so (and the charge is unproven), it was a tactical triumph but a strategic error.

The Snowden story is full of puzzles and suspicious twists and turns. Snowdenistas are extraordinarily paranoid about the actions of their own governments, yet they and their media allies are strangely trusting about the aims and capabilities of the government of Russia—where Mr. Snowden arrived so oddly and lives so secretly.