PARIS — Following the third deadly terrorist attack Britain has suffered in less than three months, Prime Minister Theresa May vowed to review her country’s counterterrorism strategy.

While May condemned what she called the “evil ideology of Islamist extremism,” the thrust of her new counterterrorism demands focused on a far more technical matter: the Internet.

“We cannot allow this ideology the safe space it needs to breed,” May said Sunday, speaking outside 10 Downing Street. “Yet that is precisely what the Internet — and the big companies that provide Internet-based services — provide.”

It has become a common practice among those behind Europe’s terrorist attacks to communicate with one another via encrypted messaging platforms such as Viber and WhatsApp.

In a March vehicle attack outside Parliament that killed four pedestrians and a police officer, the perpetrator, Khalid Masood, 52, was revealed by British media to have been communicating on WhatsApp just minutes beforehand. This prompted Britain’s Home Secretary Amber Rudd to implore that messaging services “don’t provide a secret place for terrorists to communicate with each other.”