Ask anyone what the two biggest foreign stories are right now and they will almost certainly say the fight against Ebola and tackling Islamic State (IS) jihadists.

Both stories have also been playing heavily on the mind of a man who himself is no stranger to making headlines.

I'm talking here about Erik Prince. Never heard of him? Well most likely you will at least know of the company he founded, the private security contractors known as Blackwater. Mr Prince has no connection with Blackwater now, having sold up and moved on to pastures new in the world of what are known as PMSCs (Private Military and Security Companies). But more of that in a moment.

Blackwater, which has gone through numerous "rebranding" changes as Xe Services before taking its now innocuous name of Academi, has itself been in the news of late.

A few weeks ago a US jury convicted four of its former ­security guards - three for manslaughter and one for murder. Their conviction stems from one of the most notorious incidents in the Iraq War.

It was back in September 16, 2007, when these Blackwater employees, assigned to protect a US State Department convoy, opened fire on civilians in Nisour Square, Baghdad, killing 17 of them.

Their recent trial has once again opened up the murky world of PMSCs, the controversy fuelled further by the latest remarks and activities of Mr Prince.

Let's take Ebola to start with. Just a day after the four former Blackwater employees were convicted, Mr Prince went on the record in an interview outlining how private contractors could be used in the battle to contain the Ebola virus. "One of the real core competencies of Blackwater, or companies like Blackwater, is we can operate in difficult places without any outside support," he told US-based Foreign Policy magazine.

The 45-year-old former Navy SEAL, now a billionaire, went on to describe how the entire operation could be "containerised": food, medicine, field hospitals, tents, water purification, generators, fuel, "everything you'd need for a humanitarian disaster".

But it is not just Ebola that Mr Prince sees as a scourge ripe for the intervention of PMSCs. He made news again in September by criticising the strategy of ­President Barack Obama's ­administration and its "failure" in taking on the IS in Iraq and Syria.

"If the administration cannot rally the political nerve or funding to send adequate active duty ground forces to answer the call, let the private sector finish the job," he said, throwing down the gauntlet to the White House.

Guns for hire, US and other mercenaries are the way to go, Mr Prince believes, when it comes to taking on IS jihadists and their ilk.

"If the old Blackwater team were still together, I have high confidence that a multi-brigade-size unit of veteran American contractors or a multi-national force could be rapidly assembled and deployed to be that necessary ground combat team," he wrote recently, underlining his position on the website of his new company. That new company is known as Frontier Services Group (FSG), described as an "Africa-focused security and logistics company", and has close ties to China's largest state-owned conglomerate, Citic Group.

It's no secret, of course, that Beijing is doing all it can to tap into Africa's natural resources, including $1 trillion in planned spending on roads, railways and airports by 2025.

This is just the kind of environment that Mr Prince and PMSCs revel in. One need only look back on his track record in Iraq, where Blackwater earned more than $1.5 billion in government contracts between 2001 and 2009 operating in various capacities, including as an overseas ­Praetorian guard for CIA and State Department officials in the borderless war launched in the immediate aftermath of 9/11.

As a Senator, Barack Obama promised he would do all he could to rein in private security companies. But the simple truth is that when he became President, a massive shadowy army of contractors continued to be deployed and remained central to his administration's global war machine throughout his first term in office.

Blackwater itself was rarely far from controversial headlines and scandals, but this didn't deter Mr Prince and PMSCs continued to flourish.

Such companies and their role, just like mercenaries themselves, are of course nothing new. So-called soldiers of fortune have been around since states first went to war. However, today's outfits are a far cry from the dogs-of-war image of past mercenaries. Today they work out of plush offices, have slick public relations machines, and websites offering "security solutions" and "logistics services". They are at one end men in suits and at the other those in Kevlar carrying weapons.

The US military ­especially is profoundly dependent on civilian contractors in the conduct of its wars. Since 2003, contractors have constituted more than 50 per cent of the force in Iraq, Afghanistan and the Balkans. PMSCs too provide more than 90 per cent of US diplomatic security, and the Department of Homeland Security spends half its budget on them.

In a time of budgetary cutbacks and constraints, normal standing armies are often viewed as simply too expensive. PMSCs are cheaper and carry no pensions or health-care costs to be picked up by government. The fact that the ­military in countries like the US and UK outsources some necessary functions is not a cause for concern in itself. Truck drivers, construction firms, laundry and catering services and technical maintenance are one thing. But the creation of a third force able independently to inflict deadly force is something else entirely.

As the Blackwater experience has frighteningly revealed, the existence of these armed ­contractors comes at great risk. In the past a few individuals have been convicted for atrocities they carried out in places like Iraq or Afghanistan, but the big money-men, chief officials and CEOs remain largely unhindered in the pursuit of their vast profits.

"The private sector has long provided nations around the world with innovative solutions to national defence problems," goes Mr Prince's argument. That may well be the case in some instances. But the private war industry remains a predominantly ­unaccountable one. Time and again in Iraq, Afghanistan and elsewhere we have witnessed the dangers inherent with subcontracting out war.

That being the case, all the more reason why there needs to be rules, regulations, guidelines and close quarters monitoring of PMSC activities, especially if they continue to function in any armed or combat role. To that end the Montreux Document of September 17, 2008 was at least a step in the right direction.

The result of an initiative launched jointly by Switzerland and the International Committee of the Red Cross, it is the first ­document of global significance to define how international law applies to the activities of PMSCs when they are operating in an armed conflict zone. Some 600 companies have signed up, but there remains a long way to go. Perhaps the most worrying thing of all is that PMSCs and their chiefs still have the ear of powerful people in high places. Unpalatable as it is, Mr Prince is right about one thing: PMSCs are here to stay.