Prior to this, the program was only available in Australia where it launched as a pilot program, but it seems that Facebook has since decided that it is good enough to be launched elsewhere. This now includes the US, the UK, and Canada so for those living in those countries can take part in it if they’re interested.
For those who are unfamiliar with this controversial program, the reason why it was controversial was because it required users to upload nudes of themselves first. The image(s) that are uploaded are then used to create a “human-unreadable, numerical fingerprint”, which means that whoever tries to upload it onto Facebook, the system will be able to recognize the image and prevent it from being uploaded at all.
Unsurprisingly the program faced a bit of backlash, although Facebook has since defended its creation suggesting that this is more of an emergency option where you would try to preempt the photos from being uploaded if you have knowledge that there are plans to do so.