According to Interior Minister Amber Rudd, providing terrorists with a place to hide and depriving authorities of access to information that could be life-saving is "completely unacceptable."
"We need to make sure that organizations like WhatsApp, and there are plenty of others like that, don't provide a secret place for terrorists to communicate with each other," Rudd told the BBC.
According to Home Secretary, if the country's intelligence services and law enforcement can't be given access to encoded communications upon the government's request, tragedies like the Westminster Bridge attack are inevitable.
"We have to have a situation where we can have our security services get into the terrorists' communications. That's absolutely the case," she argued.
Foreign Secretary Boris Johnson also expressed concern with encrypted messaging apps in an interview with the Sunday Times, and called on technology companies to create a software that would detect and remove extremist material.
It emerged on Sunday that Masood had been on the radar of the intelligence community for potential links to extremism since 2010, after he returned from teaching English in Saudi Arabia.