New details are emerging today on the masked ISIS terrorist who beheaded American journalist James Foley.

The terrorist who carried out the beheading in a YouTube video spoke with a distinct British accent, leading to suspicion that he may be one of many British citizens who have traveled to Syria and Iraq to join ISIS or other extremist groups.

In an interview with Gretchen Carlson, Feature Story News correspondent Simon Marks called it a clear attempt by ISIS to "up the ante" against the U.S. by having the British-sounding man carry out the execution.

A Guardian newspaper report quoted a former hostage who had been held in Syria, saying he recognized the voice of the masked man and believed it was a terrorist who went by the nickname "John."

The former hostage said that he and others being held in Syria actually started calling their British-sounding captors "The Beatles."

And now, a Newsweek report points out this startling figure:

There are now more than twice as many British Muslims fighting for Islamic State than there are serving in the British armed forces, according to a British Member of Parliament (MP).

Khalid Mahmood, the MP for Perry Barr in Birmingham, estimates that at least 1,500 young British Muslims have been recruited by extremists fighting in Iraq and Syria in the last three years.

Mahmood told Newsweek that this figure had been building since the start of the Syrian conflict: "If you look across the whole of the country, and the various communities involved, 500 going over each year would be a conservative estimate.”

According to the Ministry of Defence, there are only around 600 British Muslims currently serving in the Armed Forces, making up approximately around 0.4% of total personnel. 4.3% of the British population are Muslim.

Watch the full discussion above.