The Who Dares Wins trooper is understood to have used an American-made McMillan TAC-50 sniper rifle that fires huge .50 calibre rounds
Sources told the Daily Star on Sunday the sharpshooter had just 15 seconds to pull the trigger as the target got out of a vehicle on the Syrian border.
The source said: “The shot was one in a million. Getting a one-round, one-kill headshot at night using thermal imagery in a 15-second target window is about as close to impossible as you can get but he pulled it off.
“He is definitely the best sniper around at the moment.”
It is understood the solider is a sergeant with the SAS G-Squadron and has carried out numerous operations in Iraq and Afghanistan racking up more than 100 confirmed kills.
The elite British unit has been deployed in counter-terrorist operations in Syria and Iraq in the past three months.
SAS Favourite Robin Horsfall is set to host an evening this Saturday 24th March in Stockton-On-Tees
Robin said " This will be the first time I have done a public event and I have chosen Julie Cooper's place in Stockton because of all the marvelous support she gives to our veterans and current Armed Forces."
"The evening starts with a 60-70 minute presentation, during which I will try to take you through the story of a bullied lonely and isolated boy who leaves home at 15 to join the army. His trials and tribulations and his adventures."
"The bullied boy becomes a paratrooper at 17, an SAS soldier at 21, a mercenary, bodyguard and top martial artist."
"There are tours of Northern Ireland, bombs and bullets, The Iranian Embassy siege in London, a suicide mission into Argentina, battles in Africa, but this is more than just a 'gas em bash em and smash em' story, the missions are there, the bombs and the suffering but this is also the story of a personal discovery and of personal development, about a boy who falls in love with a special woman, of a man who's first son is born 4 days after the enemy surrender in the Falklands war, of a human being who has to learn to stand on his own two feet and manage with little or no help."
"I want to share my story with you, and then give you as much time as possible to ask your questions."
Tickets are still available for £20 each at http://www.britisharmedforcesthebest.com/product-page/tickets-an-evening-with-robin-horsfall
Limited tickets will be on sale on the door for £25.