A gauge tracking near-term price swings in the Japanese yen climbed on Monday, approaching a six-week high as traders grappled with the prospect of more inflationary pressure on one hand and Bank of Japan warnings against a quick surge in bond yields on the other.

One-month USD/JPY implied volatility rose for a second time in three days to 10.77%, on course for the highest close since Jan. 15.

Investors seem to be divided on how quickly policymakers should withdraw their monetary stimulus. The country’s inflation accelerated more than forecast last week, and this week’s Tokyo CPI reading is expected to reinforce that narrative of more rate hikes.

Expectations of more policy tightening have helped the yen rally nearly 4% in February, putting it on track for one of the best performances among 16 major currencies tracked by Bloomberg.

Bank of Japan Governor Kazuo Ueda on Friday signaled readiness to intervene in the bond market to quell soaring yields, which prompted the yen to trim gains. Any follow-up actions in the coming weeks could lead to more price swings in the currency, even as its outlook for more appreciation remains intact.

On Monday, one-month USD/JPY risk reversals traded at 1.46% in favor of puts, which suggests markets see more yen gains in the month to come. Traders are paying much more for put options that look for dollar-yen to fall than calls that bet on the currency pair to rise.