The head of the International Monetary Fund says the United States and other wealthy nations need to urgently tackle mounting global debt levels that are weighing heaviest on low-income countries. IMF Managing Director Kristalina Georgieva said Wednesday that just trying to grow the U.S. economy out of its more than $40 trillion in national debt would not suffice. Speaking at the autumn meeting of the IMF and World Bank in Bangkok, she said the U.S. needs to save more, China should spend more and Europe should increase investment levels. Georgieva and other financial leaders say rising debt and global inflation have pushed interest rates to multidecade highs, adding to the debt burdens of the world's poorest nations.