"What we may see here maybe in a way a more striking conclusion, that is that in a free and open society, even when you do everything right, you still may not be able to prevent a group of people willing to kill themselves using relatively low tech means," Rep. Adam B. Schiff, D-Calif., said on CNN's "State of the Union" Sunday.
Sen. Coats, R-Ind., agreed with Schiff.
"Intel is not 100 percent perfect. The Russians really did not give us specific information," he said.
The discussion comes after news the Russian government intercepted a call between the mother of the bombers and someone who may have been one of her sons.
That discussion may have covered a possible jihad, host of the show Candy Crowley said.
Schiff said the Russian government did not communicate everything it knew, and he argued for better cooperation between the Russian and U.S. governments.
"There's got to be a basis for why they went up on her electronically or why they went up on one of her affiliates or associates," Schiff said. "We don't know that. We haven't received that information from the Russians. I think they do know more than they're telling us."