Dhaka, May 9 -- Warren Buffett made his name advising devotees never to bet against the United States. Yet even Uncle Sam's greatest fan is implicitly questioning whether the days of US outperformance are over. When he announced plans to bow out on Saturday, Buffett's Berkshire Hathaway was less focused on America Inc than ever before, with over half of its investment portfolio in cash and its highest ever weighting to non-US assets.

Yet 48 hours later at the Milken Institute Global Conference, Scott Bessent took up Buffett's old baton with relish, urging his audience to go all-in on the United States. The entirety of the country's economic history, quipped the Treasury secretary, can be distilled in just five words: "Up and to the right...