Speaking at a State Department event, Brennan addressed the importance of both accepting refugees from Syria and maintaining security safeguards to keep terrorists from exploiting the resettlement program.
"There is no other country on the face of the earth that is more of a melting pot than the United States," said Brennan, "and so what we want to do is make sure that we are able to maintain our commitment to those values and the things that have made this country great."
"At the same time," he added, "I think it makes it even more incumbent on the security and intelligence professionals to make sure that we are able to look at individuals who are coming into this country with an eye toward what it is that we might know about individuals or ways that terrorist organizations might try to secret people into these networks, into these refugee flows."
Brennan said he is determined to "see what we can do to strengthen that system that allows us to have as best insight as possible into the backgrounds of these individuals as well as what their intentions might be."
The U.S. refugee resettlement program has come under intense scrutiny in recent days after it was revealed that one of the attackers in Friday's Paris attack may have entered Europe by posing as a refugee.
Since then, more than half of U.S. governors have refused to accept new Syrian refugees, and Speaker of the House Paul Ryan has called for a pause in the program.
In his remarks on Wednesday, Brennan also spoke about the importance of striking a balance between civil liberties and national security in the digital domain in order for the government to protect its citizens.
"What we need to be able to do is to make sure that we understand what that appropriate role is for the government in that digital domain," said Brennan. "Because if the government's primary responsibility is to care for the security and welfare of its people, it needs to do that in all of the domains."
"I don't think we're there yet as far as being able to understand all of the dimensions of that domain," he added shortly after.
Brennan also spoke more broadly about recent terror attacks, such as the one in Paris, noting that these incidents "redouble the determination of intelligence and security professionals to make sure we do our jobs the best we can."
"Every day around the globe, law enforcement, security, intelligence agencies, are taking actions that disrupt the plans, the intentions and activities of these terrorist organizations," he said. "Unfortunately, some get through. And I think this is what we have seen over the last several weeks."
Secretary of State John Kerry, speaking after Brennan as part of the same event, took a different approach to the CIA chief, seemingly dismissing critics of U.S. refugee resettlement policy.
"We're going to do the right thing by refugees," Kerry said. "I mean, how is it that somebody can suddenly say that a 50-year-old woman with her grandchildren is going to be a threat? That we can't process people adequately to keep faith with our values in this country?"
Kerry also spoke in support of the administration's broader Syria policy, including its participation in diplomatic talks on a political transition -- talks that have brought it to the negotiating table with Russia and Iran, who support Syrian President Bashar al-Assad.
"I'm convinced that if we are clever, creative, patient, tenacious, persistent and steady, we will have the ability to be able to destroy Daesh," Kerry said, using another term for ISIS, "and in the doing of that, send a message to Boko Haram, to Al Shabaab, to Al Qaeda, to any other entities in the world, that the world will stand united against barbarism and against an attack on our very purpose and reasonableness itself."