The UK government has unveiled a tool it says can accurately detect jihadist content and block it from being viewed.
Home Secretary Amber Rudd told the BBC she would not rule out forcing technology companies to use it by law.
Ms Rudd is visiting the US to meet tech companies to discuss the idea, as well as other efforts to tackle extremism.
Thousands of hours of content posted by the Islamic State group was run past the tool, in order to "train" it to automatically spot extremist material.
It is said the software is capable of detecting 94% of IS's online activity, with an accuracy of 99.995%.
Anything the software was not sure about would then be flagged up for a human decision to be taken.
Laws May Force Facebook & Twitter To Use This
It is intended to lighten the moderation burden faced by small companies that may not have the resources to effectively tackle extremist material being posted on their sites.
Sites such as Facebook and Twitter may soon be forced to using this software on their networks.
"We're not going to rule out taking legislative action if we need to do it," the home secretary said.
"But I remain convinced that the best way to take real action, to have the best outcomes, is to have an industry-led forum like the one we've got."
The bigger challenge is predicting which parts of the internet that jihadis will use next.
The Home Office estimates that between July and the end of 2017, extremist material appeared in almost 150 web services that had not been used for such propaganda before.
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