Runaway government debt could sink markets and slam the economy, 2 watchdogs warn

• The soaring national debt threatens to cause market chaos and economic pain, two watchdogs warned.
• The US government's ballooning interest payments are eating a hole in its budget, they said.
• Investors have brushed off the threat but there's a risk of a UK-style market meltdown.

The US government is racking up dangerous amounts of debt, raising the risk of a market meltdown and economic disaster, two fiscal watchdogs warned.