TOKYO (Reuters) -Japan's leading trade negotiator said on Tuesday that the trade deal Tokyo agreed with the United States last week guarantees Japan will always receive the lowest tariff rate on chips and pharmaceuticals of all the pacts negotiated by Washington.

Trump said the U.S. will impose a 15% tariff on Japanese imports under the agreement, which he hailed as "maybe the largest deal in history."

That's down from the 25% levies he proposed earlier this month. Japan's prime minister says duties on autos from his nation will be cut to 15% from 25%.

"The trade deal struck with the U.S. is certainly a relief in that it offers some certainty that U.S. tariffs on Japan-made cars won't rise to punitive levels," said Stefan Angrick, head of Japan and Frontier market economics at Moody's Analytics.

It is the most significant of a clutch of agreements Trump has bagged since unveiling sweeping global levies in April, though like other deals, exact details remained unclear.

U.S. automakers worry that President Donald Trump’s agreement to tariff Japanese vehicles at 15% would put them at a competitive disadvantage, saying they will face steeper import taxes on steel, aluminum and parts than their competitors,

The deal reduces tariffs on Japanese exports, including autos and auto parts, to15 percent, in exchange for Japanese investment and import commitments.

TACO or tariffs? An August 1 deadline looms after the European Union became the latest of the top US trading partners to reach a deal with Trump.