Alex Stamos, chief information security officer at Yahoo, said that if technology companies were obliged to provide "backdoor" access to their systems for the US government, they would face heavy pressure to do the same in China and Russia.
Admiral Mike Rogers, who took over at the NSA last year, said it would be "technically feasible" for companies to hand over information to law enforcement but this had to take place within an agreed legal framework.
The sharp exchange of words was the latest signal of the growing dispute between Washington and Silicon Valley over new end-to-end encryption technologies which started to gain considerable prominence in the wake of the Edward Snowden leaks about the NSA.
In one example of the new security technologies, the latest operating systems for Apple and Google smartphones include strong encryption that the companies themselves cannot break. For many industry executives and privacy experts, these types of encryption are likely to be the best defence for customers against their data being hacked.
However, senior US officials have warned that the growing use of encryption could make it harder for law enforcement to solve homicides or find victims of child exploitation. "The post-Snowden pendulum has swung too far in one direction," FBI director James Comey said last year.
Mr Stamos was questioning the contention of Mr Comey and some other officials that the US authorities should have the technical means of getting access to user information if they have a warrant or another legal authority.
