Secretary of State John Kerry assured Congress that the United States intelligence community, eager to avoid the kind of mistakes that preceded the invasion of Iraq, has gone to great lengths to verify Syrian dictator Bashar Assad's culpability for a recent chemical weapons attack.

"We were here for that [Iraq war] vote," the former Democratic senator told the Senate Foreign Relations Committee, referring to himself and Secretary of Defense Chuck Hagel, who served as Nebraska's senator. "Our intelligence community has scrubbed and rescrubbed the evidence" in order to provide accurate information to Congress about the chemical weapons attack.

"We can tell you beyond any reasonable doubt that our evidence proves the Assad regime prepared for this attack, issued instructions [for the attack], warned its own forces to use gas masks," Kerry continued, noting also that the chemical weapons rockets fell exclusively in opposition-controlled areas.

"We know these things beyond the reasonable doubt that is the standard [that must be reached] to send people to jail for the rest of their lives," he said before calling for Congress to help enforce "the world's red line" against the use of chemical weapons.