The ultimate test facing the Japan-U.S. joint intervention: Can the yen break through the "death line" of 155? Bank of America warns that if it fails, the authorities will have no cards left to play.

The Zhitong Financial APP noticed that the historic joint intervention by Japan and the United States is shifting the market focus to whether the yen can break through 155 yen to 1 dollar. Strategists believe this threshold is a critical test to determine whether the yen's rebound momentum can be sustained.