The U.S. and UK have teamed up to put pressure on Facebook.
They've urged it to drop plans for encrypted messaging - unless law enforcement officials can get backdoor access.
The pair also signed an agreement that will allow them to fast track requests for information about messages sent by suspected terrorists and child predators.
The deal was announced Thursday by UK Home Secretary Priti Patel and U.S. Attorney General William Barr:
(SOUNDBITE) (English) U.S. ATTORNEY GENERAL, WILLIAM BARR, SAYING:
"This agreement will make it much easier for our governments to obtain evidence directly from these companies and greatly accelerate the investigative process and ultimately make people much safer. Save lives, save children."
The agreement will cover all messaging services, including those run by Apple and Google.
But right now it's Facebook under the most pressure, thanks to its encryption plans.
Messaging services are widely used by pedophiles to groom victims and exchange images.
Priti Patel says Mark Zuckerberg's company mustn't duck the issue:
(SOUNDBITE) (English) BRITISH INTERIOR MINISTER, PRITI PATEL, SAYING:
"So I would really urge Facebook to engage with us in active dialogue which is something that has not happened thus far. That's why we've signed this letter."
Facebook has strongly opposed the creation of any back doors.
On Thursday Zuckerberg said he was optimistic that the social network could identify predators, even in encrypted systems.
He said Facebook might also further limit the ways adults can interact with minors.