"Those who have spoken out against this agreement, including many in this chamber, and those who have made every effort to thwart the diplomatic process are many of the same people who spoke out forcefully and irresponsibly about the need to go to war in Iraq," Sanders said on Wednesday.

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Sanders, who is running for the Democratic presidential nomination, added that supporters of the Iraq War were "wrong then, they are wrong now. Unfortunately, these individuals have learned nothing from the results of that disastrous policy."

Sanders, who supports the Iran nuclear agreement, said that while the military option must remain on the table that "it should be the last option."

"I fear that many of my Republican colleagues do not understand that war must be a last resort," he said. "It's easy to give great speeches about how tough we are, but let us not forget the cost of war on the men and women who serve in our military."

Sanders comments come as the Senate formally opened debate on a resolution of disapproval for the Iran nuclear agreement.

Congress has until Sept. 17 to pass a resolution on the Iran deal, with 42 senators backing the agreement.