President Trump’s decision to negotiate a break for China on tariffs is galling for Japan, which is reeling from auto sector levies that the White House has shown no sign of willingness to lift.

Japan, a top U.S. ally in Asia, was eager to advance trade negotiations with Washington, even as Mr. Trump imposed tariffs on automobiles, and threatened an across-the-board 24 percent tariff on Japanese goods.

While Beijing and others assembled plans for retaliatory tariffs, Japan rushed to Washington for trade negotiations, armed instead with commitments to buy more American goods and boost investments in the United States to $1 trillion.

Now in Tokyo, the sting is palpable.

On Tuesday — one day after the Trump administration agreed to temporarily nix most of its tariffs on China — two of Japan’s top automakers issued dire profit forecasts, weighed down by the effects of U.S. car tariffs.

Honda Motor said that its operating profit would fall nearly 60 percent for the fiscal year that began in April. It attributed the downgrade to a whopping $4.4 billion hit from tariffs.

Nissan Motor suspended its profit forecast for the current year, and said that it would likely swing to an operating loss in the first quarter. The automaker, which was already restructuring its global operations before the U.S. tariffs, said it would slash an additional 11,000 jobs on top of the 9,000 cuts it announced in November.