Use of Zoom and other digital communications has soared as many Americans have been ordered to stay home to slow the spread of coronavirus.

SpaceX’s ban on Zoom Video Communications Inc illustrates the mounting challenges facing aerospace manufacturers as they develop technology deemed vital to national security while also trying to keep employees safe from the fast-spreading respiratory illness.

In an email dated March 28, SpaceX told employees that all access to Zoom had been disabled with immediate effect.

“We understand that many of us were using this tool for conferences and meeting support,” SpaceX said in the message. “Please use email, text or phone as alternate means of communication.”

Two people familiar with the matter confirmed the contents of the mail.

A representative for SpaceX, which has more than 6,000 employees, did not respond to a request for comment. Chief Executive Musk also heads electric car maker Tesla Inc.

NASA, one of SpaceX’s biggest customers, also prohibits its employees from using Zoom, said Stephanie Schierholz, a spokeswoman for the U.S. space agency.

The Federal Bureau of Investigation’s Boston office on Monday issued a warning about Zoom, telling users not to make meetings on the site public or share links widely after it received two reports of unidentified individuals invading school sessions, a phenomenon known as “zoombombing.”

Investigative news site The Intercept on Tuesday reported that Zoom video is not end-to-end encrypted between meeting participants, and that the company could view sessions.

"We want to start by apologizing for the confusion we have caused by incorrectly suggesting that Zoom meetings were capable of using end-to-end encryption," the company said in a blog post. "Zoom has always strived to use encryption to protect content in as many scenarios as possible, and in that spirit, we used the term end-to-end encryption." (bit.ly/2xH3Et8)

The company added that it encrypts all content from Zoom meetings where everyone is using the Zoom app and the sessions are not being recorded. It said it was unable to currently encrypt content when users log in using other devices.

Zoom did not immediately respond to requests for comment on SpaceX’s decision.

As a defence contractor, California-based SpaceX has been classified as an essential business, allowing it to stay open through shutdowns in California and Texas, the development and testing hub for its Starship rocket that could be used to get to the moon and Mars and send national security satellites to space.