The Villains - Spoilers

Who were they? First off, it's suggested that it's a drug cartel. That explains the Xavier connection. Then, it's some successor to the KGB (the FSB?) or possibly the government of "Kagistan" (?). But why would they want to kill the President, and what would be the diplomatic ramifications if they did? Maybe this is explained in the book, or in an earlier version of the script...