President Donald Trump on Sunday announced a major trade agreement with the European Union, the biggest deal yet as he seeks to revamp the global trading system and shore up domestic manufacturing.

The decision follows negotiations that led to the release of 10 American prisoners in the county.

Big change in the military is typically framed as a “revolution” or “transformation” and is almost always about “innovating” and “adapting” to new technology. Yet the most important—and most worrisome ...