The US has declined to join an international initiative aimed at tackling the spread of terror online.
The White House said today that it supported the Christchurch Call's aims but was "not currently in a position to join the endorsement".
The comments came as five of the world's biggest tech companies pledged to tackle extremist material online.
Facebook, Amazon, Google, Twitter and Microsoft will develop shared tools to detect and remove terrorist or extremist content among other measures.
The pledge was made at a Paris summit, which was called after the terror attack in Christchurch, New Zealand left 51 people dead.
The March attack was live‑streamed on social media.
French President Emmanuel Macron hosted the event with New Zealand Prime Minister Jacinda Ardern, who has been calling for technology executives to sign a pledge as the "Christchurch Call".