In an appearance on ABC's "This Week," the senator said President Barack Obama was right to draw a "red line" about the tolerance of the use of chemical weapons in Syria's civil war.
"Well, I think frankly he should have made it clear, as he did, that ... the systemic use of chemical weapons against the Syrian people is something the international community cannot tolerate," he said after earlier comments by Sen. John McCain, R-Ariz., who condemned Obama for inaction.
"The president by saying red line, he gave a green light to all of [these] massacres," McCain said. "And it's a shameful chapter in American history."
Reed said the United States should be cautious in how it reacts to reports of chemical weapon use.
"I think we have to take it very seriously. I think we do have to be careful, though, because we've had situations in the past where we've acted on information that was incomplete, impartial and frankly, to the detriment of our country and national security," Reed said. "Now, the question is, what do you do? You can't do it hastily. But you have to do it very deliberately. And I believe that's what the president is trying to do."
Earlier on the program, McCain accused the Obama administration of covering up information regarding the Benghazi investigation.
His comments came after ABC News obtained emails showing that the State Department edited out references to al-Qaida and terror from the CIA's talking points about the attack.
"I would call it a coverup in the extent that there was willful removal of information, which was obvious," McCain, R-Ariz., said during his appearance on ABC's "This Week."
McCain also criticized White House spokesperson Jay Carney for saying that the CIA was responsible for the talking points and that the administration had only suggested revisions.
"For the president's spokesman to say, well there was only words, or technical changes made in those emails, is a flat out untruth," he said.
Reed disagreed with McCain and said there was no coverup.
"The Congress has already had 11 hearings on the topic, over 25,000 pieces of documentation have been provided to the Congress," he said.
Reed also argued that the talking points were the product of a number of agencies that agreed upon what to say.
"Well, what they did, I think, was try in a very chaotic situation, to come up with points that they felt confident of," he said. "They didn't want to go too far in two concepts. One, our intelligence resources or assets that you might not want to disclose. Second, there's an ongoing investigation was just beginning. Those two factors also framed the response."