SAN FRANCISCO — At a time when Russian hackers are reported to have intervened to sway the U.S. election, the threat of state-backed cyberattacks has never seemed so real. But for businesses that have long been in the crosshairs of foreign interests, finding a way to respond has remained stubbornly hard.

Diplomatic efforts, such as sanctions or bilateral dialogues, have been ineffective or run into roadblocks. Law enforcement actions, like the U.S. Department of Justice’s indictment of Chinese People’s Liberation Army (PLA) officers, have been announced with fanfare but with few actual results.