If you’re talking about ISIS, pretty much everyone in various ways. They purchase a lot of their arms from countries like North Korea and some of the ‘stans. A lot of their arms are purchased on the black markets of southern Europe, as well. There is a shitload of armament left over from the 1990’s wars in the Balkans, now in the hands of unscrupulous dealers such as the Neapolitan Mafia and other orgs and individuals.
They have had control of large, productive oil fields in the Middle East such as those in eastern Syria and, until very recently, those around oil-rich Mosul in northern Iraq, the oil of which they sell on the black market, the paperwork of which is then laundered, then the oil is resold onto the world oil marketplace in Rotterdam.
The laundering of the paperwork which obviously isn’t very effective in hiding the provenance of the oil, serves to give plausible deniability to the buyer. Nobody is really fooled by the process.
But if a retired nurse isolated on a small island in the Caribbean knows about this, so do the people who buy this high quality oil at bargain rates much below market price, including U.S, Canadian and many European companies without hindrance of international authorities whose job it is to prevent things like this from happening.. And in this way, the US, Canada, Germany and many other European countries arm ISIS. It is the height of hypocrisy, but nobody is doing anything to stop it. .