Japan’s Shinzo Abe told U.S. President Donald Trump that it’s dangerous to broach the topic of currencies, the prime minister said on Sunday.

The comment came in a television debate with lawmaker Shigeru Ishiba, his rival in the ruling Liberal Democratic Party leadership election on Thursday, as Abe addressed U.S.-Japan relations.

He added that Trump hasn’t attacked Japan on the topic of currencies since their first meeting. In January 2017, Trump said Japan and China “play the devaluation market,” a charge Japan’s top currency official refuted.

Asked about Japan’s public finances, Abe said Japan needs to fully escape deflation in order to achieve fiscal consolidation. A sales tax hike planned for October 2019 will proceed unless there is another crisis on the level of the Lehman Brothers bankruptcy, he said.

Abe also addressed a surprise offer from Russian President Vladimir Putin to conclude a peace treaty between the two countries by the end of the year, which Japan rejected earlier this month. He said many experts think Japan should take a more proactive approach, and that a meeting between the leaders later this year would be “important.”

Abe and Ishiba are running for the top spot in the LDP. A victory by Abe in the Sept. 20 election would put him on course to become the country’s longest-serving premier.