There is a "high probability" that Syria used chemical weapons during fighting with opposition forces, though a final verification is needed, U.S. Rep. Mike Rogers, chairman of the House Intelligence Committee, told CNN's Wolf Blitzer on Tuesday.

"I have a high probability to believe that chemical weapons were used," Rogers, R-Michigan, told CNN. "We need that final verification, but given everything we know over the last year and a half, I would come to the conclusion that they are either positioned for use, and ready to do that, or in fact have been used."

Rogers and Sen. Dianne Feinstein, D-California, chairwoman of the Senate Intelligence Committee, struck ominous tones in an interview on CNN's "Situation Room" about the possibility that Syria had crossed what President Barack Obama has said was a "red line" that could lead to the United States' getting involved militarily in the conflict.