Taiwan's government throttled national internet access this week, a self-inflicted outage built into the annual Han Kuang exercises and designed to answer one question: can the island coordinate a defense without the network Beijing would move first to sever. The drill runs alongside war games simulating missile strikes and special-forces incursions, the two scenarios Taipei's planners treat as the opening moves of an actual invasion, not the follow-on.

Retired Rear Adm. Mark Montgomery's warning that Russia is transferring submarine-quieting technology to China lands the same week, and it changes what the blackout drill is rehearsing for. A quieter Chinese submarine fleet closes the gap Taiwan's navy has counted on to detect a blockade before it tightens, which means the communications failure Taipei is now testing for isn't a hypothetical cyberattack. It's the plausible opening minutes of a naval encirclement Taiwan may get less warning of than it did a year ago.