The Japanese yen has weakened past the 160 mark against the U.S. dollar, underscoring its vulnerability to further losses and raising the likelihood that Japanese authorities will step in once again to curb the currency's slide. While the precise threshold for intervention remains uncertain, strategists warned on Monday that several price levels could trigger renewed action, starting at 161 and extending into the 162-163 zone.

Still, analysts maintain that any such move would likely only buy time rather than deliver a lasting solution. The yen has already given back more than half of the gains achieved during the record intervention campaign that began in late July, reflecting the persistent downward pressure.

The latest leg of weakness was driven by broad dollar strength on Friday, as traders bought the greenback on expectations of higher U.S. interest rates. This reinforces the view that much of the yen's trajectory lies beyond Tokyo's control. Since the United States and Japan jointly purchased yen in July for the first time since 1998, the currency has repeatedly failed to break through the 155 level, and it now faces renewed downside momentum.

Rinto Maruyama, senior rates and foreign exchange strategist at SMBC Nikko Securities, noted that 161 is the first level to watch, followed by the 162.9-163.3 range, which corresponds to the zone where authorities last intervened. He added that the government's approach during the previous round of action placed significant emphasis on maintaining an element of surprise, meaning Tokyo could act at any moment without warning.

The yen was trading at 159.77 against the dollar, roughly 0.2% stronger than its New York close of around 160.09 on Friday.