Some conspiracy theorists conclude that the US covertly supported the rise of Isis and al-Qaeda, but a more credible accusation is that Washington and its allies created the conditions in which they flourished.
This was a calamitous error in judgement: when the Syrian army withdrew from northern and eastern Syria in 2012, it created a vacuum that was swiftly filled by al-Qaeda fanatics. Revolt in Syria restarted the sectarian civil war in Iraq. Isis captured Raqqa and Mosul, spread to the rest of the Islamic world and began its terrorist attacks in western Europe.
The same catastrophic mistake is now being made again as Western military forces ready themselves to attack Syria. Contrary to the pretence by the governments of the US, UK and France that their great concern is the sufferings of the Syrian people, their actions will simply deepen these because their only likely impact will be to lengthen the war.