The Islamic State released a video featuring a young boy in military fatigues and an older masked man speaking in a British accent.

Reuters reports the video, which has not been independently verified as of yet, also showed the killing of five men accused of being Western spies.

The masked militant's accent and dress called to mind the now diseased British ISIS member Mohammed Emwazi, often referred to as "Jihadi John." He too appeared as the face of the terror group in a number of videos in which hostages were executed.

Emwazi is believed to be dead following an airstrike in Raqqa last fall that specifically aimed to eliminate the British militant.

In this latest video, the new masked man specifically called out British Prime Minister David Cameron, labeling him a "slave of the White House" and a "mule of the Jews."

"How strange it is that a leader of a small island threatens us with a handful of planes. One would have thought you'd have learned the lessons of your pathetic master in Washington and his failed campaign against the Islamic State," the man said.

He also referred to the prime minister as an "imbecile" for provoking and angering the Islamic State.

Cameron told reporters Monday that the video was a tool of propaganda used by a "desperate" and weakening organization.

"This is an organization that's losing territory, it's losing ground ... Britain will never be cowed by this sort of terrorism, our values are so much stronger than theirs. It may take a very long time but they will be defeated," the prime minister said.

The video ended with a young boy with an ISIS headband speaking in English to the camera. The boy, seemingly no older than 4 or 5 years old, said, "Go kill the kuffar [unbelievers] right over there."

A spokeswoman for Cameron said Britain is continuing to examine the video.