Rick Rieder, BlackRock’s chief investment officer for global fixed income, says Japan’s efforts to prop up the yen will require hawkish signals from the Bank of Japan, not just government intervention in currency markets. He speaks in an interview for Bloomberg Television’s Wall Street Week with David Westin.

Supporting the yen will take more than government intervention and will need hawkish signals from the Bank of Japan, said Rieder. Japan’s currency has edged back toward 160 per dollar this week, once again approaching its cheapest level in four decades.

The move unwinds some of the US-Japanese efforts to strengthen it at the turn of the month and underscores the limits of intervention in the face of interest-rate differentials that favor the dollar.