When American spy satellites photographed clear signs that India was preparing for a nuclear test in 1995, Frank Wisner Jr., then the United States Ambassador to India, showed the photographs to top Indian officials in a successful effort to persuade them not to test. It was a triumph of intelligence and diplomacy's working together to stop the spread of nuclear weapons.

But some officials now say success sowed the seeds of the failure to anticipate India's five nuclear tests this month. Showing the photos to the Indians revealed how the United States had spied on the test site, they say, and thus enabled the Indians to conceal their preparations this time -- for instance, by burying the cables and wires running into the shaft where they conducted the tests.

''You're showing your capabilities to the very people trying to conceal things from you,'' an official said, adding that an investigation into the failure to foresee the tests asks, ''Did we help them go to school in some way?''

A State Department official said such worries were baseless. But this dispute arises whenever the Administration chooses to use secret intelligence to discourage Russia, China and other nations from spreading weapons technology.