The Bank of Japan's equivocation on its inflation target is adding to the shifting global monetary policy picture that has sparked a sovereign debt rout.

The nation's 10-year yield has climbed almost 10 basis points since BOJ Gov. Haruhiko Kuroda said April 30 that he sees the price goal being reached around the first half of the 2016 fiscal year. When Kuroda introduced his record bond-buying plan in April 2013, he said he expected the goal would be reached in about two years.

The change in tone is an admission of failure that suggests the need for further easing, which is technically difficult and requires a new policy regime, according to Tokai Tokyo Securities Co.