The latter could be targeted in a revived and enlarged version of Operation Gideon, the 1970s era Mossad project that eventually tracked down and eliminated every one of the 1972 Munich Olympic terrorists.
Such an operation need not involve a great deal of bloodshed: a bomb-designing geek in Amsterdam turns up dead in a canal some morning, a shady banker falls down the stairs in Rome, a rabid neo-Streicher propagandist perishes in a car wreck near Manchester, mysterious raiders hit a terrorist-affiliated drug-lab in the hinterland of Paraguay and burn it to the ground, a private jet from Saudi Arabia disappears over the Indian Ocean, taking a prince of the realm with it.
None other than arch-liberal Bob Simon of CBS News advocates a variation of this for the US war on terror. He cites an often overlooked advantage of the Gideon style operation: nobody even claims that it is legal, and it does not therefore require changes in the law that might be abused later.