A boom in recruitment by security firms guarding ships against Somali pirates has caused a stream of troops to leave elite units for lucrative contracts in the private sector.
The loss of veterans of wars in Afghanistan and Iraq, particularly corporals and sergeants, "rips the skeleton" from the bodies of units like the Royal Marines and Parachute Regiment, the commander of 3 Commando during the Falklands War, Julian Thompson, has warned.
According to Ministry of Defence figures, 570 Royal Marines and 170 members of 2nd and 3rd Battalions of the Parachute Regiment left the forces between 2009 and 2011.
Even though the figure for the Marines includes those who were medically discharged, the rate at which elite soldiers from both units have been leaving is around double the average.
Among the Marines, the MoD admitted, the bulk of those leaving voluntarily were senior privates, corporals and sergeants. These non-commissioned officers lead sections of around eight men, or platoons of around 30. They are responsible for life-and-death tactical decisions during fighting.
No definite data is available on what soldiers do when they leave the services but senior officers have been deeply concerned about the losses of experienced troops to the private security companies for more than a year.
"Anecdotally, between 1st June 2011 and 30th November 2011, 54 soldiers from 3 Para have applied for Premature Voluntary Release. Of these, 24 have claimed they were seeking work in the private security industry," an MoD source said.
Britain is the world leader in security companies, which have expanded rapidly into the maritime sector as a consequence of piracy in the Indian Ocean and Arabian Sea.
Recent estimates put the economic costs of piracy at \$7bn over the last three years.
At times piracy has threatened to have a strategic impact on countries like the UK because 40% of its liquid natural gas passes through the Suez Canal and interruptions in supply could have driven prices up.
A private security contractor with a background in the Marines or Paras can expect to earn around £300 a day - up to triple what they could earn in the forces. Typically they work in small teams of around four men and travel on board ships crossing the Indian Ocean. Some are armed.
Maritime security insiders say part of the reason the private sector is able to recruit so easily is that the frequency of deployments to Iraq and Afghanistan has taken a heavy toll on the private lives of soldiers and their families.
They are also aware that their chances of avoiding death or a life changing injury decline with every tour on the front line. Some units who have been involved in the heaviest fighting in Afghanistan since 2006 have suffered casualty rates of one in five.
"Everyone seems to think at some stage my number might be up, whether it's one tour or two tours or however many tours," said Ben Scott, a former Royal Marine corporal who served for seven years and fought in Helmand in 2007.
"If you have that feeling it certainly puts the wind up you. You might not want to really do it anymore, it's not a risk you're going to want to take,"
He left the commandos six weeks ago and is soon to start work guarding ships in the Indian ocean for Plymouth-based Transafe Maritime.
Phil Cole, a director at Maritime Asset Security and Training, which has offices at Stansted and Plymouth in order to maintain close links to nearby Paras and Marines, said that companies looked for mature soldiers who have held leadership positions.
"The jobs on the ships require maturity and quick thinking. Our guys will be required to liaise with government officials, the ship's master, and to face off with pirates. That means that we will be looking to recruit men and women who have been leaders in the forces - often those who have retired or are leaving after a few years because they want a quieter life and better pay.
"The down side is that we don't offer the job security that the forces do. All of our people are self-employed," he added.
But recruitment of NCOs poses a risk to units because "it rips the skeleton out of the structure".
"The structure is built around the skeleton of the junior commanders and they are absolutely vital to make certain that their expertise is passed on to the young guys and they do the leading then the kitchen gets hot," Major General Thompson said.
As a result the Royal Marines have boosted the number of soldiers being trained to be corporals and sergeants.
"To compensate for a slight increase in early service leavers, the capacity at the Commando Training Centre in Lympstone has been increased and extra instructors have been allocated to boost the number of Junior and Senior Command Courses that are required for promotion," the MoD said in a statement.
Marines who sign on for an extra three years beyond their existing contracts are also paid a £15,000 lump sum - and they have been spared from any cuts under the MoD's efforts to balance a budget, which has been £39bn in the red.
Public support in the UK for the war in Afghanistan has been falling. Nearly three-quarters (73%) believe it is unwinnable, according to a recent ComRes poll. In June last year the figure was 60%, while 46% of those surveyed had no idea why Britain was in Afghanistan.
Nonetheless, recruitment to the Armed Forces, including the Royal Marines and Paras, remains strong.
"We know we have a problem with our junior leaders being attracted from some units into the private sector but there is no shortage of recruits, so in the long term this will be balanced out," said an MoD source.
An official statement from the ministry said: "Those who serve in the Armed Forces build up specialist skills over the course of their Service.
"The Services place great value on these, which is why we offer a wide range of benefits to those serving, including housing, an excellent pension scheme and a clear career progression."