The UK government is set to get support from the European Union in its attempts to see the final WhatsApp message sent by Westminster attacker Khalid Masood.
After it emerged Masood had sent a message on the app, mere minutes before killing four people and injuring up to 40 others, the Government has called on WhatsApp to show it the message.
The messaging service uses end-to-end encryption to ensure the privacy of its billion users, saying the protection of its personal messages is a core principle for the company.
Amber Rudd, who previously told the BBC it was "unacceptable" for the service to allow terrorists to communicate in secret, has traveled to Brussels for a meeting on Monday with ministers from the other 27 member-states, who many say would be inclined to support the UK's case.
Germany and France in particular are likely to back the motion, having suffered several high-profile terror attacks.
Both countries have lobbied the European Commission to force tech companies to reduce the encryption services they use to protect messages.
A spokeswoman for Whatsapp has said the company is "co-operating" with investigating officers in the attack on Westminster, while Amber Rudd is due to meet with representatives from it and other tech companies at the Home Office on Thursday.