Apple and Google are adding their names to an open letter to President Barack Obama asking him to quash any moves to create “backdoor” access to encrypted data on smartphones and other communication devices.

More than 140 tech firms, civil society organizations, and cryptologists have signed a letter to be sent on Tuesday, though the Washington Post says it has obtained a copy of it in advance. “Strong encryption is the cornerstone of the modern information economy’s security,” the co-penned letter says.

The issue of online security and encryption has never been far from mainstream headlines since whistleblower Edward Snowden made a series of revelations about how the National Security Agency (NSA) mines data from private communications. Some of the major tech companies have also been accused of complicitly allowing the government access to backdoor portals to their data.

Last year, both Apple and Google revealed they were now encrypting their phones’ data by default, which led to some public comments from the FBI, saying it was “concerned,” explaining why it might need access to people’s private communications.

“I am a huge believer in the rule of law, but I also believe that no one in this country is beyond the law,” said FBI Director James Comey. “What concerns me about this is companies marketing something expressly to allow people to place themselves beyond the law.”

U.S. authorities have increasingly voiced their concern that by not being able to access private communications due to encryption, it loses intelligence that prevents it from intercepting criminal activity. So while both the FBI and Justice Department have openly said that they support the use of encryption, they ultimately want a way to circumvent it when required.

This duality ultimately leads to a tricky situation. Any so-called “backdoor” that’s built-in to a technology for one body to use could also be accessible by hackers or other foreign threats.

The Washington Post says that the letter being sent today includes the signatures of three of the five members of a review group appointed by President Obama in 2013 in the wake of the Snowden leaks.

Ultimately, the letter is seeking to add weight to the pro-privacy movement, and urges the government to “fully support and not undermine efforts to create encryption standards.” It also calls for the government to not “weaken” commercial software.