US debt hits $40 trillion as economists warn of a debt spiral

US public debt has surpassed $40 trillion, and economists are sounding the alarm over a growing debt spiral. Fiscal policy expert Marc Goldwein said: "The most terrifying thing is that you can watch a debt spiral begin with your own eyes." Poorly-designed tax laws, tariff decisions and costs linked to the war with Iran are cited among the factors deepening the problem.