Moody's says the United States and other Western nations have moved "substantially" closer to the point of losing their top-drawer credit ratings, the NYT reports today. And the countries won't be able to repay what they owe -- currently $12.6 trillion -- relying only on economic growth. That means tax increases and/or budget cuts -- and the U.S. loves its Medicare and other entitlements so much that budget cuts alone won't work.