Japan’s top currency official on Wednesday indicated he had no issue with growing market expectations over Bank of Japan interest-rate hikes, which this week helped send the yen to a four-month high.

“There is no gap with my view,” Atsushi Mimura, the vice finance minister for international affairs, said in reference to the market’s understanding of recent BOJ communications. Mimura was speaking to reporters in Cape Town, South Africa, on the sidelines of a meeting of Group of 20 finance chiefs and central bank representatives.

Mimura noted that Japan’s recent economic indicators registered robust growth and illustrated elevated inflation. BOJ Governor Kazuo Ueda has said that the bank will raise rates if its economic outlook is realized, after lifting the benchmark to 0.5% last month.

Further BOJ rate changes would narrow a gap in interest rates with the US, putting pressure on the Japanese currency to gain. With the BOJ’s policy rate still relatively low, a weak yen has kept authorities on high alert in the past few years. Japan spent about ¥15 trillion ($101 billion) to shore up the yen last year.

Mimura also highlighted the need for vigilance over any potential excessive moves in foreign exchange rates. The yen gained this week on the back of increasing speculation on BOJ rate hikes, and also rising demand for haven assets — thanks in part due to escalating global trade tension.

“Amid high uncertainty, we have to keep watching the impact of any speculative trading on, not only the exchange market, but also financial markets overall,” Mimura said.

Japan’s currency rose to as high as 148.57 per dollar, the strongest level since last October, on Tuesday in New York. It has climbed by the most among major currencies in the past month.