Five years ago, the military-industrial complex went on high alert when it started to look like lawmakers would fail to avert sequestration budget cuts.

Pentagon leaders marched up to Congress, arms stuffed with briefing slides showing giant red arrows pointing downward. The military’s ground force, they said, would shrink to its smallest size since 1940, and the Navy’s fleet would plummet to only 230 ships, the fewest since 1915.