A year after criticizing U.S. fiscal policy as “irresponsible,” China’s leaders are showing increasing confidence in President Barack Obama’s leadership of the American economy.The Cold War was defined by a competition between two military superpowers; the post-Cold War world is all about the fusing of two economic superpowers. The global becoming is Sino-American.China boosted holdings of Treasury notes and bonds by 2.6 percent to $900.2 billion in March and April, after reducing its stake by 6.5 percent from November through February, the longest consecutive monthly declines in a decade, U.S. data released June 15 showed. The People’s Bank of China said June 19 that it will relax its 23-month lock on the yuan.