Japanese government officials are faced with a challenging question: when to begin the work of clearing up misunderstandings caused by U.S. presidential candidate Donald Trump’s remarks about bilateral relations?

On the campaign trail seeking the Republican Party’s presidential nomination Trump criticized Japan, along with China and Mexico, saying Tokyo has deliberately lowered the yen’s value against the dollar, making American products less competitive and hurting U.S. employment.

Bringing jobs back from Japan and other countries has become his signature phrase to please the crowds. The 69-year-old billionaire businessman also claims the 1960 bilateral security treaty is unfair as it only obliges the United States to defend Japan.

“We have a trade deficit with China of $500 billion a year. We have a trade deficit with Japan of over $100 billion a year,” Trump told a press conference after winning in three primaries Tuesday. He blasted Japan for buying “practically nothing” from the United States.

Trump said Japanese construction machinery manufacturer Komatsu Ltd. threatens its American competitor, Caterpillar Inc., thanks to what he called Japanese currency manipulation.

Some senior Japanese government officials and Washington-based experts on bilateral relations said that while Tokyo recognizes Trump’s rhetoric is over the top, it is hard to identify whom to raise this with on his staff.

The U.S. goods trade deficit with Japan amounted to $69 billion and that with China stood at $366 billion in 2015, according to the U.S. Commerce Department.

Trump continues to be the front-runner in the presidential nomination race both in terms of support ratings in opinion polls and the number of delegates secured so far.

“I’ll refrain from commenting on him,” Japanese Ambassador Kenichiro Sasae told a recent press conference after being asked for his views, apparently out of concern that any hasty bid to correct Trump’s statements could backfire.

One of the Japanese officials said, “We don’t think now is the best time” to challenge Trump as he is not thought to have set up a full-fledged foreign policy team.

Trump’s solid popularity, in spite of his derogatory remarks about Hispanics, Muslims and others, and the growing possibility of him becoming the Republican presidential candidate in July, have been making big headlines in Japan for months.

If Trump wins the nomination, even if he does not become the next U.S. president, “it will have a negative effect” on bilateral relations between the United States and Japan, James Schoff, a Washington-based expert, said.

“There will be a little bit less trust, less confidence by Japan in America writ large,” said Schoff, senior associate of the Asia Program of the Carnegie Endowment for International Peace think tank.

In early March a group of Republican security experts, including former Cabinet members, released an open letter criticizing Trump’s remarks on foreign policy, saying, “We are united in our opposition to a Donald Trump presidency.”

“His insistence that close allies such as Japan must pay vast sums for protection is the sentiment of a racketeer, not the leader of the alliances that have served us so well since World War II,” they said. The undersigned included former Homeland Security Secretary Michael Chertoff and former Trade Representative Robert Zoellick.

Japan earmarked ¥189.9 billion to host U.S. military bases in Japan in the current fiscal year through March 31.

Trump also criticized a sweeping free trade deal President Barack Obama’s administration signed with Japan and 10 other Pacific Rim countries.

Approval by the U.S. Congress is necessary for the Trans-Pacific Partnership to take effect, but Trump and other candidates such as former Secretary of State Hillary Clinton, who leads the Democratic nomination race, are critical of the initiative.

“Every month that goes by I think it gets harder and harder,” Schoff said, referring to passage of the TPP through the legislature, given Trump’s growing sway over the Republican Party, which normally has been supportive of free trade.

“That would have a long-term impact on … America’s reputation in the region and on that issue going forward,” Schoff said.