PALO ALTO, Calif.—To hear Google Inc. Executive Chairman Eric Schmidt tell it, the U.S. government has only itself to blame for new efforts by Google and Apple Inc. to keep police out of suspects’ smartphones.

Speaking at a round table of technology executives organized by Sen. Ron Wyden (D., Ore.), Mr. Schmidt offered Silicon Valley’s first public retort in a renewed debate about how far technology companies should go to protect user data.

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