Well this one ISP in Pakistan chose to effectuate the block for its subscribers in a rather unusual way.

We reiterate that there must be concrete ways of providing assistance and cooperation to promote and effectuate the peaceful use of nuclear, chemical and biological agents, materials, technology and equipment, in particular in order to promote the social and economic development of developing countries.

(b) The priority rules set forth in section I of the annex and will effectuate such rules by use of a registration system that fulfils the purposes of such rules, in which case, for the purposes of section I of the annex, registration pursuant to such a system has the same effect as registration pursuant to section II of the annex