US Interest ÷ Defense Spending

## What this measures

Federal interest payments (BEA, A091RC1Q027SBEA) divided by national defense spending (BEA, FDEFX), both at seasonally adjusted annual rates.

## Why it matters

The line where the cost of past borrowing overtakes the cost of present security. The historian Niall Ferguson treats the crossing as a warning sign for a great power; Habsburg Spain, ancien-régime France and interwar Britain all crossed it.

## How to read it

1.0 is the crossing. Above it, every rate rise competes with the defense budget for room.

## What it does not say

National-accounts basis; it excludes veterans' benefits and some defense-related spending outside FDEFX.

## Source

Derived by Palanor from BEA NIPA data via FRED.