This could well be a leftest group, but I think they may have some new friends. When you consider Chavez's hostility toward Mexico and the US and his "strategic partnership" with Iran as well as bringing in the new central American leftists into that partnership, it is very possible that this is an indirect attack on the US energy supply by two countries who want to drive up the cost of oil. Iran has certainly used proxies in the past to achieve its objectives and I would not rule out its involvement at this time. Since the US is Pemex's best customer, I think it would be a mistake to rule out the involvement of Iran and Venezuela, especially on the funding end.