4GW non-state actors are already committing economic warfare against us and other states. They have been for over a decade. Most of their attacks are formulated on "strategic convergence" that centers around meeting several strategic concerns. Three basic "convergences" include economic, highly public and casualty saturated. Whether that is two attacks on the WTC (1993 and 9/11/2001), the Madrid trains (full of commuters on their way to work), the London Bombings (full of commuters on their way to work), Bali night clubs (tourism), Sharm El Sheikh (tourism), Moroccan Synagogue (tourism), Saudi Arabian oil refinery, Oil pipelines in Iraq, blowing up markets in Iraq, kidnapping people from businesses, taking over the western Anbar smuggling crime rings (one of the reasons the Anbar tribes were getting ticked off; they were interfering with their hereditary business that had sustained them even through Saddam's reign), Piracy of the coast of Somali (interdicting shipping through the suez) and on and on and on.

One of my previous posts from two years ago was about Al Qaida's War for Oil and other things:

This is a map of the Ottoman Empire (caliphate)[see link for maps] at the height of its power from the 15th to early 18th century. It's power was not derived simply by military might. As you can see by the map to the left of the legendary "silk road", it controlled major maritime and land routes, vast amounts of raw resources including base metals, precious metals, precious and semi-precious gems, grain, rice, cotton or muslin, ink, silk, precious woods, papyrus (for making paper), tea and even part of the opium trade (just to name a few). The wealth of the empire helped to produce some of the major changes in medicine, engineering, literature, basic science and philosophy. All this long before the discovery of petroleum.[snip]

Today, Islamist organizations are attempting to regain power in many of these states. And, just like centuries past, these states sit on top of some of the world's largest natural resources and straddles the world's busiest maritime routes. The map on the right shows modern maritime routes that follow the same path as the "silk road" routes with the exception that the Suez Canal has greatly reduced the number of days that it takes to bring products and energy resources to Europe, Russia, Australia, Japan, China and the United States to name a few.

The long term goals of this movement is known. They seek to create an Islamic Caliphate or state that would encompass the original area of the caliphate at the height of its power. They seek to accomplish this goal by supporting Islamist movements through out these areas with the intent of creating slow (or quick) erosion and take over of the most vulnerable states. Even if all of the states within the area do not "flip" to Islamism, the creation of Islamic states in key areas would drastically change the control of key materials, production and maritime routes. If these Islamic states make economic and security compacts with one another, it would formulate the seeds of a wider "caliphate" and potentially dominate neighboring states, not to mention create whole new paradigms for inter-state and international conflict. Any and all movements in this direction could and would be used to damage or control world economics, specifically western economics.[snip]

In the short term, reviewing the contested areas, maritime routes, materials and production, the strategy to "vex and exhaust" the United States, its allies and other target states, does not require the actual take over of any one state and does include a wider economic strategy beyond "military" or "political" cost. Generally, these movements only require that the area or country stays in turmoil, thus increasing the cost of production, exporting, importing and transporting goods as well as securing ports. For instance, 18 of 20 highest volume container ports are in South East Asia. Basically, the strategy of "a thousand cuts".
Check the link for much more including a list of over ten basic resources like steel, cotton, rubber, grains, rice and a multitude of technology that is transported through these routes or come from nations within the scope of the hoped for "caliphate". I address the Suez Canal later in the piece. Sharm El Sheikh in the Sinai could have equally been a destabilizing attack to try to provide room for operations or just cause enough insecurity to have nations shipping things through a much longer (additional ten days) around South Africa. In a JIT (just in time inventory) world, 10 days is a life time. The costs of shipping would be increased by higher insurance rates and much higher diesel fuel utilization, thus higher costs. Along with rising oil prices, this could be extremely detrimental to the world economy.

This is 4GW Economic Warfare at its base. Additional thoughts on North Africa and the "levant" here

Attacks on stock markets can occur by non-state actors with ease. A number of huge trades on the stock market just prior to the 9/11 attacks were traced back to front companies with ties to Islamic terrorist organizations. Whether these trades were simply meant to remove money from a possible crashing market post attacks and preserve funds for operations or the trades were meant to destabilize the market is a good question. Either way, it's non-state actors practicing economic war at the individual or micro-level.

It can be devastating if we let it.