US Army Staff Sergeant Eric Ferguson gets into full battle gear prior to a mission in Khost Province, eastern Afghanistan, on July 1. Ted Aljibe / Agence France-Presse

CAMP SALERNO, Afghanistan - Who says soldiering is a young man's game?

Staff Sergeant Eric Ferguson joined the US Army in 1973 and - now approaching his 60th birthday - he is still on active duty, leading distribution convoys through some of the most dangerous parts of Afghanistan.

Armed with an M4 machine gun, Ferguson supervises trucks as they inch their way across the eastern province of Khost delivering ammunition, rations and maintenance supplies to troops stationed in remote combat outposts.

Roadside bombs are a constant threat. One exploded just ahead of his most recent convoy, causing a nerve-wracking four-hour wait as specialist route clearance teams arrived to find a safe way ahead.

But for Ferguson, the life of a soldier is uniquely rewarding and entirely suitable for a man who will turn 60 on Jan 14.

"I enjoy the camaraderie, and I love my soldiers," he said. "They make you laugh at the things they say.

"They are mostly in their 20s and they are often surprised when they hear how old I am, but they soon realize I am just one of the guys."

Ferguson, who shows few signs of his veteran status besides flecks of gray in his clipped moustache, goes to the gym every morning and also turns out for his platoon basketball team.

"Playing with younger guys, it wears you out. They don't give me a break, they're hard," he said. "I passed my medical no problem last month, and I'm blessed to be as fit and healthy as I am."

The 39 men and three woman in his CLIP (combat logistics patrol) platoon gently tease him about his age, and have nicknamed him "Old Gravy Bones" - which he has written on the door of his tiny office.

"I don't know, I guess it means I'm old and strong," he says with a shrug.

Ferguson expected to stay in the army for just three years when he signed up 38 years ago, but found he came to like military life more and more.

Then he served as a part-time reservist in the national guard for many years before rejoining fulltime in 2008 and he will finally hang up his uniform in June.

"You have to leave before you turn 62, and next year I will have done the 20 years of active service that mean you get paid a pension and other benefits," he said.

It will be a well-earned reward for Ferguson, who served in Germany, Hungary and Iraq before his two tours of Afghanistan.

Only last year, while deployed in the eastern Afghan city of Jalalabad, he was using his machine gun in battle to beat off insurgent ambushes and firefights.

"We've had a couple of scares but haven't had any injuries so far this time," he said of his current deployment based at Camp Salerno in Khost province, where US troops battle with Taliban rebels.

"I could chose to stay here on the base, but I think I should be out with my soldiers most days, even if we have to spend 12 hours or more on the road," he said, sitting next to his 10 kg flak jacket.

Ferguson, who has four children between the ages of 25 and 33, finds that being four decades older than the youngest soldiers means some naturally gravitate to him for advice.

"Because of the experience I have, I talk to them about their plans to marry, about divorces, and whether to stay in the army. This generation is marrying young and divorcing young, there's a lot of that going on, he said.

Agence France-Presse