Two former U.S. Treasury Secretaries issue warnings about the risks facing the U.S. Treasury bond market.

Two former officials who served as U.S. Treasury secretaries during the global financial crisis are warning about the risks facing the $29 trillion U.S. government bond market, covering issues ranging from unsustainable fiscal paths to concerns about the Washington political system. Regarding federal borrowing, "our current trajectory is unsustainable," former U.S. Treasury Secretary Henry Paulson said in an interview with CNBC on Tuesday. "I don't know whether that means we hit a wall in six months, or six years, or whenever." Timothy Geithner, who succeeded Paulson in early 2009, said in the same interview with CNBC that the 10-year U.S. Treasury yield is "at a pretty moderate level, reflecting some basic confidence that we will govern ourselves rationally." Geithner stated, "But it depends ultimately on whether that system can restore some balance between revenues and spending, bring down the deficits a bit," and maintain the elements that give people confidence in U.S. government bonds, such as rule of law and the independence of the Federal Reserve. "These aspects are currently facing greater shadows compared to the past period."