Washington steps in to save Tokyo’s weakened currency in first joint yen-buying action for almost 30 years, causing its value to surge.

Coordination between Japan and the United States now appears to be the tightest in decades, fuelling one of the most notable rebounds since the yen began its years-long slide.

It was Washington's first yen-buying intervention with Tokyo in more than a decade as it languishes near 40-year lows.