People and groups with extensive technical skills and expertise of military value who are willing to sell their services to the highest bidder irrespective of the consequences to human life. Such services may be negotiated on an individual basis or through a variety of legal fronts, such as a network of corporations operating in several countries.
Recent examples include networks of western corporations supplying expertise for the construction of chemical weapon factories or sophisticated missiles. Such activity may be accepted as perfectly legal in some countries. In others the physical export of such technology may be illegal but not the specialized knowledge to design or operate it.
The government sanctioned military-industrial complexes of a number of countries undertake the sale of such technology to countries which would normally be considered irresponsible, or unlikely to use such technology to maintain the peace.