Following fierce congressional criticism, the Commerce Department said it will try to inspect all U.S. supercomputers sold to Russia and China instead of relying on those countries to verify their end use.

The pledge came after a storm of objections earlier this week to a proposed Commerce rule that calls for self-reporting by supercomputer buyers in countries considered to be nuclear risks.In November, Congress passed an amendment that requires end use checks for computers faster than 2,000 million theoretical operations per second (MTOPS) because of reported diversions to nuclear and missile programs in Russia and China last year.

Commerce responded with a regulation to implement the new export law by asking foreign buyers to file reports, identifying their names, addresses and the intended uses for the machines.

The proposed rule makes no mention of separate post-shipment verifications by U.S. agencies, officials confirmed. The self-reporting provision has been ridiculed as ''postcard verification'' by arms control advocates.

''The idea is moronic,'' a congressional aide said Wednesday after The Journal of Commerce reported on the regulation.

But in an interview, William Reinsch, Commerce undersecretary for export administration, said the agency always planned to conduct its own post-shipment verifications, although the legal requirement is not spelled out in the rule.

''It is our intent to do as many as we can,'' said Mr. Reinsch. ''This was simply an attempt to get more information than we might be able to get from the exporter.''

It was not clear why Commerce officials failed to state earlier that there would be separate U.S. inspections. Mr. Reinsch said the officials were not responsible for enforcement, and he insisted the rule should not have to include language on the verifications required under the law.

''It does not comment and will not comment on what we might do with the information,'' said Mr. Reinsch. But the agency appears headed for a confrontation with Congress over what the regulation does and does not say.

''They have to fix the rule,'' said an aide to Sen. Thad Cochran, R-Miss., chairman of an international security panel of the Senate Governmental Affairs Committee, which launched a withering attack on the administration's anti-proliferation efforts in a majority report this week. ''If they don't do that, there are other options available,'' the aide said.

The Cochran subcommittee charged that the United States ''has itself become a proliferater, however unintentionally, due to the Clinton administration's policy liberalizing export controls on dual-use technologies like supercomputers.''

The reference is to Mr. Clinton's 1995 move to end license restrictions on computers up to 7,000 MTOPS for civilian end users in Russia and China. In November, Congress largely reversed that decision by requiring prenotification to U.S. agencies before the export can take place, along with post-shipment verification of end use.

In its report, the Senate also cited information from Mr. Reinsch in charging that the administration has failed even to request post-shipment verifications for 47 supercomputers sold to China, as well as the machines diverted to nuclear arms projects in the Russian cities of Chelyabinsk-70 and Arzamas-16.

Mr. Reinsch called the subcommittee's conclusions ''a masterpiece of selective quotation.''

''It is simply not true to say that we have not asked the Russians to visit the two sites in question,'' said Mr. Reinsch, confirming that Russia has not complied with the request.

The issue of whether to keep selling supercomputers to countries that refuse to allow inspections seems likely to come up in Congress this year. China has refused to allow inspections by U.S. officials, according to a General Accounting Office report last year.

''I think they should lose eligibility for exports if there's a lack of cooperation,'' said Gary Milhollin, director of the Wisconsin Project on Nuclear Arms Control. The law requires Commerce to report to Congress on cases where it has been unable to conduct end user checks.

Mr. Reinsch continued to argue that the burden of conducting post-shipment verifications will be heavy. Although advocates say that supercomputer exports to Russia and China have averaged only about one a week, Mr. Reinsch said the rate has more than doubled since last March.