Speaking at a daily press briefing, Carney told reporters that "there must be a response" after last week's poison gas attack in the suburbs of Syrian capital Damascus.
"We cannot allow this kind of violation of an international norm with all the attendant grave consequences that it represents, to go unanswered," Carney said.
He said US President Barack Obama has been reviewing options with his team and "we will consult with the Congress for the options for Syria."
"He consults with international allies and as his administration consults with the Congress, about what the appropriate response to this flagrant violation of international norms should be," Carney added.
Carney noted that "even though the inspection team was 45 minutes away, they blocked access for five days as they bombarded the neighborhoods to try to eliminate the evidence of chemical weapons use."
"The course of action has not been decided on," Carney said as a response to question whether the president will seek U.N. approval or some sort of backing on Syria.
Carney said that the US president had not made a decision on how US would respond to Syria after the chemical weapon attack.
In a response to a question whether Obama made any decision in the last 24 hours on what the US response to the Syrian chemical weapons attack would be, Carney said that "the president continues to work with his national security team, reviewing the options available to him. And when he has made a decision and has an announcement to make, he'll make it. So that process continues."
"Both Secretary Kerry and I attempted to make clear yesterday that there is no doubt here that chemical weapons were used on a massive scale on August 21st outside of Damascus. There is also very little doubt, and should be no doubt for anyone who approaches this logically, that the Syrian regime is responsible for the use of chemical weapons on August 21st outside of Damascus. We have established with a high degree of confidence that the Syrian regime has used chemical weapons already in this conflict
"We have made clear that it is our firm assessment that the Syrian regime has maintained control of the stockpile of chemical weapons in Syria throughout this conflict."
He said that "we know that the regime maintains custody of the chemical weapons in Syria and uses the types of rockets that were used to deliver chemical weapons on August 21st. That opposition does not," Carney said.
"We completely agree that there is no military solution to the conflict in Syria, that there has to be a political transition, and we are engaged in a process with many countries as well as with the opposition to help bring about that transition. In the meantime, as Assad continues to brutally assault and murder his own people, we have provided assistance and stepped up assistance to the military opposition in Syria, as we helped the opposition unify," said Carney.
- "Turkey felt significant consequences as a result of this conflict"
Carney noted, "when we talk about the instability in the region and the volatility of the region, that Syria borders an ally, a NATO ally of the United States, in Turkey, and a close friend and partner of the United States in Jordan. And both those nations have felt significant consequences as a result of this conflict and have a great deal at stake when we talk about the use and proliferation of chemical weapons."