Six months ago two Louisiana sheriffs were shot to death and two more injured in the parking lot of a Valero oil refinery. Six years ago Saudi police halted a pair of armed terrorist attacks on the world’s largest refinery, in one case opening fire on a car that exploded near the facility’s gates.

Guns are more than a theoretical issue for the energy business, which controls much of the world’s most vital – and most vulnerable infrastructure. As the US contends with a public debate given new urgency by a series of high-profile shootings, the issue of security and gun control in and around key energy infrastructure is once again front of mind for many of the bodies charged with monitoring energy security and devising responses to potential threats.

In a way, the comparative peace that has reigned over US energy infrastructure in the past decade is remarkable. Accidents like the Macondo spill and blackouts like those from Sandy have not been the handiwork of terrorists, despite the fact that much of the sector’s key infrastructure is surprisingly easy to access. Drive along the same stretch of Mississippi River refineries where the Louisiana shooting occurred in August 2012 and – while the facilities are gated – the transportation infrastructure around can be driven up to and around without a single sign of security.

Not a New Thing

The issue of protection for energy infrastructure and the potential for armed violence against energy facilities is hardly a new one, even though it remains – like much of the energy business – largely invisible to the end consumer.

Oil fields from Nigeria to Colombia have been subject to armed attacks as part of local politics, and coal trains in Colombia headed for export facilities have traditionally traveled with armed guards to stave off attacks on infrastructure. On a larger scale, the most potent guns are probably the ones that are never or rarely fired – the arms of the US military that hold open much of the globes’ energy trade throughways like the straights of Hormuz.

There remains an awareness though – even in the developed world where visible armed security is rare – of the potential risk of energy infrastructure for surrounding communities. Proponents of liquefied natural gas facilities and transportation of LNG have had to cite the science for dispersal of the fuel in case of an explosion or attack (a former Shell director told Breaking Energy it would disperse into the upper environment because of its chemical makeup rather than exploding, making it safe to ship through narrow waterways like Turkey’s Bosphorus).

In the days immediately after the 9/11 terrorist attacks, the nuclear industry was forced to reconsider its security profile. Plants were retrofitted to withstand a direct hit from an airplane (listen to an Breaking Energy podcast on the subject here), while guards at nuclear power plants were permitted to carry heavy duty firearms and – in 2009 – carrying guns at nuclear power plants was finally declared a federal crime.

This story is part of an AOL series examining gun violence and the gun debate in America. See Guns in America: How guns affect jobs, money, culture and communities in America.

In March 2009 the regulations governing the number of armed responders required at nuclear plants to rise to “not less than ten.” Earlier regulations had left room for the number of armed guards to be as low as five, determined on a case by case basis by the Nuclear Regulatory Commission, a report from the Congressional Research Service shows.

The report notes serious lapses despite the upgrades in security. Video recordings in 2007 of “inattentive” security offers at Exelon’s Peach Bottom nuclear plant “drew harsh criticism” from Congress and resulted in further regulations that strengthened a 2005 Act requiring NRC to conduct intensive war-game style security exercises at nuclear plants at least once every three years.

The federal government has overall taken an aggressive approach to assessing, if not diminishing, security risks to the US energy sector. The Department of Homeland Security includes the energy sector as one of 18 critical areas and works with the Department of Energy to develop regulations through the Energy Sector Government Coordinating Council. A host of other organizations also work with DHS, including the Federal Energy Regulatory Commission and the North American Electric Reliability Corporation.

A Separate Peace?

Even as efforts to protect power plants and energy infrastructure have proliferated, and energy production may proliferate in the US as energy production itself accelerates amid a boom driven by hydraulic fracturing.

The controversy around fracking in rural communities has the potential to turn violent and create security risks for drilling operations unaccustomed to facing them, consultancy Control Risks said in an unusual report on security at hydraulic fracturing operations in the US. “Three trends that could guide the future of the anti-fracking movement: expansion into new jurisdictions; incorporation into broader issue advocacy; and radicalisation of direct action against the unconventional gas industry,” the report says.

For many facilities, the increasingly interconnected nature of energy production, distribution and use makes cybersecurity a bigger risk to the system’s operation than the threat of armed violence at individual facilities.

“From broad-based threats against corporate e-mail systems to targeted spear-phishing attacks aimed at nuclear operations, utilities face new challenges regularly,” Lockheed Martin Senior Manager Rich Mahler wrote in a post for Breaking Energy recently. “A focus area is the regular increase of vulnerabilities reported in the security of industrial control systems that monitor and control manage the power grid, as noted by the Department of Homeland Security and the media.”