A State Department survey of 161 nations found that about half of the countries face a medium to high risk of Year 2000 computer breakdowns in their telecommunications, energy and transportation sectors, which may have an impact on international trade, the department's inspector general said yesterday.

"It would be prudent to recognize that Y2K-related failures are inevitable, both here and abroad," Jacquelyn L. Williams-Bridgers, the State Department IG, told a Senate committee.

Electronic disruptions--caused by computers with two-digit date fields that incorrectly interpret "00" as 1900 instead of 2000--could range overseas from minor inconveniences, such as malfunctioning credit card terminals, to sustained power and phone outages causing economic and humanitarian hardships, the IG said.

The State Department survey, drawn from assessments submitted over the past two months by U.S. embassies, found that highly industrialized countries are at a low risk of Y2K-related infrastructure failures, particularly in the finance sector. But the survey suggested that Russia and the former Eastern Bloc nations "are a concern because of the relatively high probability of Y2K-related failures," the IG said.

Power-grid failures due to Y2K glitches could cause Russian defense systems to shut down, Pentagon officials said at a separate briefing yesterday. There is little worry about an accidental nuclear launch because Russian strategic weapons require humans to carry out key commands, but the Pentagon is concerned the Russians might lose their early-warning capabilities and feel dangerously vulnerable to a sneak attack.

As a confidence-building measure, Defense Secretary William S. Cohen said, the Russian government has been invited to send representatives to a specially built "Y2K Center for Strategic Stability" in Colorado Springs, Colo., where both nations would share instant access to early-warning information. The Russians halted cooperation with the initiative in March because of the NATO bombing campaign in Yugoslavia, and they have not agreed to resume talks.

Cohen, who had been seriously concerned a year ago that the Defense Department was moving too slowly on its computer work and made Y2K fixes a top priority, said yesterday that the Pentagon's roughly 10,000 computer systems will be ready for the Year 2000, and that more than 92 percent of all "mission critical" systems have been fixed.

Despite the State Department's "mixed" snapshot of Y2K conditions abroad, Williams-Bridgers said she is "more optimistic" now than in March, when embassies turned in their initial assessments.

The IG testified before the Senate Special Committee on the Year 2000 Technology Problem, chaired by Sens. Robert F. Bennett (R-Utah) and Christopher J. Dodd (D-Conn.). They heard from a panel representing some Fortune 500 companies, including Ford Motor Co., Philip Morris Cos. and Procter & Gamble Co. The executives said their companies have spent millions of dollars on computer repairs here and overseas and do not anticipate severe Y2K disruptions next year.

Williams-Bridgers did not identify the Y2K-troubled nations but offered some hints in her prepared testimony: South Korea got off to a late start and may not complete its Y2K work; India's electric power systems could prove vulnerable; and Poland could face power blackouts.

In response to questions, Williams-Bridgers said U.S. officials are concerned about the energy sector in Russia and Africa, and aviation in parts of Africa.

Given the array of possible Y2K problems overseas, Sen. Richard G. Lugar (R-Ind.) suggested that the U.S. government's contingency planning seemed "more relaxed than I would have anticipated."

But Williams-Bridgers said embassies are at work on backup plans in the event of unanticipated emergencies and that a "massive database" is being developed so U.S. intelligence agencies could analyze Y2K trends abroad. The State Department will notify the traveling public of any Y2K concerns in September, she said.

Despite its confidence in its Y2K fixes, the Pentagon also has developed extensive plans to deal with problems in its own systems and any breakdowns that could occur where U.S. forces are stationed.

"We are busy preparing detailed contingency plans to deal with even the most unlikely situations," Cohen said.

Defense has been conducting elaborate exercises to determine whether all the Y2K bugs have been found. Last week, for example, a test of the logistics supply chain involved more than 1,000 participants from all four services in 22 sites across the country; Cohen said further exercises will test linkages to prime vendors of military equipment.

Five comprehensive tests of the nation's strategic weapons command have included simulated firings of every nuclear weapons system, and no Y2K failures occurred during any of them, said Adm. Richard Mies, commander of the U.S. Strategic Command.

With $3.7 billion budgeted for Y2K fixes, Cohen said, "we are treating the Year 2000 as if it were a cyberattack directed at the very core of our military capabilities."