https://www.digitalhistory.uh.edu/disp_textbook.cfm?smtid=2&...

"The estimated cost of the war in Vietnam during the Kennedy, Johnson, and Nixon administrations was $176 billion."

Adjusted for inflation, that is $1,192 billion in 2026 dollars.

"The longest war in American history had significant economic effects both domestically and internationally in terms of what was spent on the war and what expenses had to be cut."

https://www.thecollector.com/vietnam-war-economic-effects/