The two young men of Chechen origin were still children when they left Chechnya. They came to the US ten years ago after having lived in Russia. Therefore, neither of them could possibly have been radicalized in Chechnya and therefore have no connection whatsoever to Saudi Arabia and Wahhabism. Neither attended mosques in the USA, radical or other. At most, the older one spent time on various websites - some radical for sure - where he learned how to make these simple bombs, and he obviously dragged his young and naive brother into his madness.
Iraqi police fire tear gas as thousands of protests burst into Green Zone, storm Parliament (AP)
from the article: The Saudi connection linking the Boston Marathon to September 11