Downgrading of US' credit rating by Standard & Poor’s from 'AAA' to 'AA+' for the first time in the history has sent shock waves across America, with many fearing this could affect the financial system worldwide. Officials in Washington , however, told US media that the agency's calculations are deeply flawed. Unnamed sources were quoted as saying that a treasury official had spotted a 2 trillion Dollar mistake in the agency's analysis. International reaction to the Downgrading of US credit rating has been mixed. China, the world's largest holder of US debt, had “every right now to demand the United States address its structural debt problems and ensure the safety of China's dollar assets,” said a commentary in the official Xinhua news agency. However, officials in Japan, South Korea and Australia have urged a calm response to the downgrade. US President Barack Obama has asked the leaders of both the Republican and Democratic parties to work together to grow the economy and get Americans back to work. In his weekly address to the nation, Obama said the Congress can take number of measures right now to spur growth and create jobs. US Senate Majority Leader Harry Reid said, the down grading reaffirms the need for a balanced approach to deficit reduction that combines spending cuts with revenue-raising measures. The Wall Street Journal termed it as shaking of the global financial system. The Washington Post said, the downgrade will push the global financial markets into unchartered territory. Reports say US is already struggling with huge debts, unemployment of 9.1 percent and fears of a possible double-dip recession.However, some analysts said with debt woes across much of the developed world, US debt remained an attractive option for investors.