First published by Money Metals here: https://www.moneymetals.com/news/2018/02/02/danger-ahead-for-us-govt-001405

The U.S. Government is in serious trouble when interest rates rise. As interest rates rise, so will the amount of money the U.S. Government will have to pay out to service its rapidly rising debt. Unfortunately, interest rates don’t have to increase all that much for the government’s interest expense to double.