But American officials say that for the first time they have found a way to hit Japan where it hurts -- and when it hurts most, with the strong yen already ravaging Japanese profits. It is unclear how long Japan's auto makers could endure the huge loss of sales that would come from a tariff that would add $20,000 to $40,000 to the cost of each car. After years of battling their way into the American luxury market, they would suddenly be surrendering it to Mercedes-Benz, BMW, Jaguar and some competitive American models.

"The U.S. is not going to stand by and watch its workers and its products unfairly treated," said Mickey Kantor, the United States trade representative, who has led the drive to be far tougher with Japan than any past administration has. Among American workers, he said, "very, very few people will be hurt."

In fact, the list Mr. Kantor announced today was more a political masterpiece than an economic one. All the cars on the list are produced in Japan, and they all make minimal use of American parts; no vehicles made at Japanese "transplants" in the United States are affected. All of the cars involved cost more than $25,000, enabling Mr. Clinton to argue that he has punished Japan without hurting middle-class American consumers. As one of Mr. Clinton's political advisers said in half-jest the other day, "So we lose the Lexus vote in Greenwich."

There are several possibilities for what could happen next. The simplest is that Japanese officials, concluding that they have misread Mr. Clinton's determination, try to patch together the minimal concessions necessary to resolve matters before the June 28 deadline. Presumably, most of the talking would take place before Mr. Clinton and Prime Minister Tomiichi Murayama meet at the conference of the Group of Seven nations in Halifax, Nova Scotia, which begins on June 15. But several Administration officials warned today that they expected the two leaders' meeting to be inconclusive and said they doubted that Japan's Government would resolve internal disputes fast enough to act before the deadline.

The second possibility is that no agreement will be reached until Japanese auto makers feel enough pain to press the politicians to solve the problem.

A third -- and probably less likely -- possibility is that Japan will decide to tough it out, for fear that caving in on autos would lead to similar pressure regarding other industries. Japanese officials could calculate that such a move would ultimately cost them less and would give them a chance to argue that the sanctions are a violation of the General Agreement on Tariffs and Trade. Many American experts on trade law say Japan could win such an argument, although Mr. Kantor insists that the United States is within its rights to act unilaterally against Japanese imports. He contends that Section 301 of the Trade Act grants broad powers to retaliate after concluding that a trading partner is discriminating against American imports. Still, he may not want to test that proposition before a neutral panel in Geneva.

Today the Director General of the World Trade Organization, Renato Ruggiero, made what some trade experts saw as a veiled warning to the United States. Mr. Ruggiero, whose appointment the United States opposed for more than a year before reluctantly endorsing him, said, "I expect both parties to abide by the W.T.O. rules and procedures, which they know well."

In public the Administration has maintained a solid front on the trade issue, trying to send Japan the message that it must make progress on the economic issues if it wants to make sure there is no damage to the political ties, and ultimately the security ties, between the countries. But several Administration officials say there are signs of growing internal tension over the issue. Mr. Kantor has called for a full-court press, several White House officials say, while Laura D'Andrea Tyson, the new head of the National Economic Council, has been trying to temper the public oratory to prevent an already nasty argument from getting uglier.