What’s behind the US army’s decision to raise enlistment age to 42?

The United States army announced last month that it would raise the maximum age at which Americans can enlist from 35 to 42 years to expand its pool of eligible candidates amid recruiting challenges in recent years.

An updated version of US Army Regulation 601–210, dated March 20, outlined the changes, including the elimination of rules requiring anyone with a single conviction for marijuana pos...