Pentagon used taxpayer money meant for masks and swabs to make jet engine parts and body armor

A $1 billion fund Congress gave the Pentagon in March to build up the country’s supplies of medical equipment has instead been mostly funneled to defense contractors and used to make things such as jet engine parts, body armor and dress uniforms.

The change illustrates how one taxpayer-backed effort to battle the novel coronavirus, which has killed more than 200,000 Americans, was instead diverted toward patching up long-standing perceived gaps in military supplies.

The Cares Act, which Congress passed earlier this year, gave the Pentagon money to “prevent, prepare for,...