"Moody’s maintains a Aaa rating on the government bonds of the United States, with a stable outlook. This rating is based on a number of characteristics of the US economy, institutions, and government finance that together support a rating embodying the lowest level of risk to bondholders. However, recent trends in and the outlook for government financial metrics in particular indicate that the level of risk, while still small, is rising and likely to continue to rise in the next several years. Although no rating action is contemplated at this time, the time frame for possible future actions appears to be shortening, and the probability of assigning a negative outlook in the coming two years is rising."
