The efforts of tech companies to disrupt online terror planning have been criticised after attacks in the UK, but one analyst says there is little they can do.
"Encryption is used to secure all our conversations online. Strong encryption enables us to do commerce and do business and communicate in a very, very secure way," security consultant Brian Honan told CNBC on Monday.
He said that asking tech companies to provide security services with special access to online communication can't be done.
"It is not possible mathematically and technically to create a back door or golden key that can only be used by law enforcement to bypass that encryption. What you are doing is weakening the strong property of encryption," said the CEO of BH Consulting.
UK Prime Minister Theresa May and her Home Secretary Amber Rudd have asked big internet firms to do more in the fight on terror.
In her speech Sunday, May called for wider regulation on companies operating in the sector.
"We cannot allow this ideology the safe space it needs to breed. Yet that is precisely what the internet, and the big companies that provide internet-based services provide," said the UK leader.
Theresa May, UK prime minister, leaves number 10 Downing Street to make a statement on the terror attack in London, UK, on Sunday, June 4, 2017.
In response, online tech giants claim they are doing all they can.
Google said it shared "the government's commitment to ensuring terrorists do not have a voice online." Facebook has pledged to make itself a "hostile environment" for terrorists.
Facebook policy director Simon Milner wrote: "Using a combination of technology and human review, we work aggressively to remove terrorist content from our platform as soon as we become aware of it."
"If we become aware of an emergency involving imminent harm to someone's safety, we notify law enforcement," Milner said Sunday.
Honan explained that tech companies also face wading through "vast amounts" of data in order to identify what might constitute a threat.
"First you have to look at whether the material crosses a boundary between free speech and democratic speech into radicalization material," he said.
"And then there needs to be clear guidelines that these companies need to be able to follow on that."
Honan said relationships between the security services and tech companies like Facebook or Apple would also have to improve.
"There has to be a greater basis for co-operation between private firms whose ultimate goal is to make a profit and those charged with protecting us," he added.