The Bush administration has its first payoff after 10 months of pressuring the Japanese to buy more American products, but members of Congress are warning much more needs to be done. The administration announced Friday an agreement designed to boost sales of U.S.-manufactured supercomputers in Japan by removing some restrictions imposed by the Japanese government. The agreement, which is expected to be formally signed in April, should open a $130 million-market for supercomputers purchased by Japanese universities and other government agencies. The breakthrough came late Thursday night following two days of intensive negotiations. U.S. Trade Representative Carla Hills said the new pact ``should give us full and effective access'' to the Japanese government market. It marked the first success for the administration since it put Japan on a ``hit list'' last April of countries accused of erecting unfair barriers to sales of American goods. Treasury Secretary Nicholas Brady, in Los Angeles for talks Friday with Japanese Finance Minister Ryutaro Hashimoto, said that with the agreement, ``We're showing that we can make some progress.'' Supercomputers were among three product areas singled out for negotiations. Little progress has been reported so far in talks on American-made satellites and wood products. ``Are (supercomputer concessions) all we want?'' Brady said. ``No. Are we going to get more? Yes. When, I can't say. I hope soon.'' The Japanese are facing a June 19 deadline to show a willingness to open their markets or face possible U.S. retaliation in increased tariffs on Japanese products sold in America. Members of Congress have been pushing the administration to take a tougher line in the trade negotiations with Tokyo, pointing to the $49 billion deficit the United States is running with Japan. That is close to half the total U.S. trade deficit last year. Sen. John Danforth, R-Mo., said the supercomputer agreement was encouraging but would have to be followed by increased sales. ``Japan must recognize that promises without performance are simply unacceptable,'' Danforth said. Sen. Max Baucus, D-Mont., noted a 1987 agreement by the Japanese to buy more American supercomputers had not produced results. He said U.S. negotiators shouldn't declare victory too soon. ``Nonetheless, progress is always encouraging. I hope this is a sign that the United States and Japan can jointly work out their trade frictions,'' said Baucus, who is chairman of the Senate Finance trade subcommittee. In addition to the product talks, the administration is conducting separate discussions on broader structural impediments to trade such as exclusionary Japanese business practices. Brady met with Hashimoto as a follow-up to trade discussions held by President Bush and Japanese Prime Minister Toshiki Kaifu. A U.S. trade official, briefing reporters in Washington on Friday, said the Japanese showed new urgency in the latest round of computer talks, apparently reflecting the impact of the Bush-Kaifu meeting. ``Their negotiators came with instructions to make a deal,'' said the official, who spoke on condition of anonymity. ``We hope the Japanese will perceive the same kind of guidance in the other issues.'' Negotiators handling the structural impediments talks met at a remote hideaway in the Virginia countryside earlier this week in advance of more formal discussions in Washington April 2-3. However, U.S. officials said the discussions near Warrenton, Va., failed to make any progress. There have been reports from Tokyo that Kaifu is preparing trade concessions in these areas in hopes of dampening growing protectionist sentiment in Congress. Under the computer agreement announced Friday, the Japanese promised to open the procurement process for supercomputers to foreign firms and to base government purchase decisions on quality as well as price.