I have read various articles concerning the subject, but wasn't going to post until I saw this one from DEBKA. Worthwhile.
The conclusion reached by debkafile’s counterterrorism and intelligence sources is that the brothers were double agents, hired by US and Saudi intelligence to penetrate the Wahhabi jihadist networks which, helped by Saudi financial institutions, had spread across the restive Russian Caucasian.
Instead, the two former Chechens betrayed their mission and went secretly over to the radical Islamist networks.
By this tortuous path, the brothers earned the dubious distinction of being the first terrorist operatives to import al Qaeda terror to the United States through a winding route outside the Middle East – the Caucasus.
This broad region encompasses the autonomous or semi-autonomous Muslim republics of Dagestan, Ingushetia, Kabardino-Balkaria, Chechnya, North Ossetia and Karachyevo-Cherkesiya, most of which the West has never heard of.
Moscow however keeps these republics on a tight military and intelligence leash, constantly putting down violent resistance by the Wahhabist cells, which draw support from certain Saudi sources and funds from the Riyadh government for building Wahhabist mosques and schools to disseminate the state religion of Saudi Arabia.
The Saudis feared that their convoluted involvement in the Caucasus would come embarrassingly to light when a Saudi student was questioned about his involvement in the bombng attacks while in a Boston hospital with badly burned hands.
They were concerned to enough to send Saudi Foreign Minister Prince Saudi al-Faisal to Washington Wednesday, April 17, in the middle of the Boston Marathon bombing crisis, for a private conversation with President Barack Obama and his national security adviser Tom Donilon on how to handle the Saudi angle of the bombing attack.
More @ DEBKA