The White House has refused to back an international commitment to prevent the spread of terrorist and violent extremist content online.
A dozen countries including the UK, France, New Zealand, Australia and Canada, as well as technology giants such as Facebook, Twitter, YouTube, Google, Amazon and Microsoft, have supported the “Christchurch Call”.
But the US has not, with the Trump administration saying it was not “currently in a position to join the endorsement”.
This may be down to broader right-wing concerns over taking some conservative commentators off social media platforms.
Earlier this month, Facebook banned far-right commentators and conspiracy theorists like Alex Jones and Milo Yiannopoulos.
And some Republicans in the US have suggested the approach disproportionately targets conservatives.
The new call to action, drafted by the French and New Zealand governments, is named after March’s Christchurch shootings targeting two mosques, where 51 people were killed by a suspected white nationalist.
Australian Brendon Tarrant is accused of carrying out the massacre.
Some of the attack was shown live on Facebook, sparking public outrage and fuelling the debate about how to better regulate social media.
The new agreement, which is not legally binding, aims to prevent similar abuses of the web while preserving “the principles of a free, open and secure internet, without compromising human rights and fundamental freedoms”.
Facebook, which owns Instagram and Whatsapp, said it is investing $7.5m (£5.8m) to improve technology to discover videos and photos which were manipulated to avoid detection.
This was the case with the Christchurch shooting, where the attacker live-streamed the massacre.
New Zealand Prime Minister Jacinda Ardern welcomed Facebook’s pledge, saying: “There is a lot more work to do, but I am pleased Facebook has taken additional steps today… and look forward to a long-term collaboration to make social media safer.”
The tech companies may join forces to develop technology or expand the use of shared digital signatures.
They have promised to reduce the risk that such content is livestreamed, including flagging it up for real-time review.
And they pledged to study how algorithms promote extremist content so they can intervene more quickly.
The White House said it will “stand with the international community in condemning terrorist and extremist content” and thanked Mrs Ardern and French President Emmanuel Macron for their efforts.
It added: “We continue to be proactive in our efforts to counter terrorist content online… while also continuing to respect freedom of expression and freedom of the press.”