"It's important for us to be able to access their communications when we can not, this will create a dead end for investigators," said the source.
Extremists usually use applications with encryption such as WhatsApp and Telegram to communicate with each other. When law enforcement can not access the message, it frustrates them.
British intelligence agencies believe they can reach an agreement that will be approved by technology companies. They hope that encrypted messages can be accessed if they get a letter for it.
During this time, major technology companies refuse to create a backdoor on their applications / services / devices. The reason, because it will make their products become unsafe.
In an official statement on its website, WhatsApp said, "We very carefully review, validate and respond to requests by the authorities in accordance with applicable laws and regulations and we prioritize emergency requests."
Apps like WhatsApp use end-to-end encryption that scrambles messages using code. So, WhatsApp can only provide metadata like account names and email addresses, but messages sent can not be delivered.