The US debt mountain is growing so fast the government could soon be spending more on interest payments than on defense

• The US's mountain of debt has become a cause of concern for investors this year.
• The government is likely to spend more on interest payments than on defense over the next five years, per Capital Group.
• The ballooning debt burden could eventually chip away at the demand for Treasury bonds, according to the investment manager.

The US's mountain of debt is growing every day – and the government could soon be spending more on interest payments than on defense, according to Capital Group.