World financial markets suffered more losses Monday, because of a U.S. credit rating downgrade, and continued European debt concerns and fears of a global economic slowdown. The firm that cut America’s AAA credit rating, Standard & Poor’s, says the United States could regain its top-tier status, but is unlikely to do so for years to come.International credit rating agency Standard & Poor's says its decision to drop the status of U.S. government one level to "AA+" was based on an analysis of the same five "pillars" in the sovereign rating framework used to determine the creditworthiness of the 126 countries that S&P evaluates.In a conference call, Standard & Poor’s executives sought to provide additional insight into Friday’s bombshell announcement, which the firm had hinted for weeks could be forthcoming, but which nevertheless came as a bitter pill to many in the United States and across the globe.S&P Managing Director John Chambers said the credit rating downgrade stemmed not only from runaway U.S. deficits and national debt, but also the expectation that America’s debt burden will grow heavier in the future. In particular, Chambers pointed to Washington’s inability to overcome political obstacles and enact aggressive fiscal reforms.“We do not foresee under…