(CNN) During a 2015 trip to Russia, Donald Trump's pick to be national security adviser, Lt. Gen. Michael Flynn, said he didn't know whether the 2013 sarin gas attack in Syria was conducted by the Syrian Army or by other forces in an attempt to draw the United States into the conflict.

Flynn not ruling out the possibility of a "false flag" attack raises questions about how the Trump administration will approach the Syrian conflict. The Obama administration , the Arab League, NATO, and many western governments have pointed to Syrian President Bashar al-Assad's regime as being responsible for the attack. A United Nations investigation didn't assign blame, but evidence from the report pointed to the Assad regime being responsible.

Assad's regime and Russian President Vladimir Putin claim opposition forces were behind the attack.

Flynn, who was the director of the Defense Intelligence Agency for the Obama administration at the time of the 2013 attack, made the remarks during a December 2015 question and answer session hosted by the Russian government-funded television network, Russia Today.

At the event, Flynn was asked by an audience member his take on reports the attack was carried out by Turkish intelligence and made to look like it was the Syrian government, otherwise known as a "false flag" operation.

"I'm going to address your question because it's a good question," Flynn said. "It's an interesting one. What keeps me up at night is the use of chemicals and biological weapons by terrorist groups that have the intent, they have the intellect, they don't necessarily have the specific types of capabilities just yet, but I believe that they will have the ability to get their hands on them. I think that all of us globally need to really pay very close attention to that."

"Your specific question, I really don't know," Flynn said. "I'm not going to sit here and tell you that I know. To have that level of knowledge or insight or detail of what an intelligence service is doing to do a false flag -- who knows. I don't have a good answer for you. I'm not able to answer your specific question."

In a 2013 op-ed in the New York Times, Putin wrote, "No one doubts that poison gas was used in Syria. But there is every reason to believe it was used not by the Syrian Army, but by opposition forces, to provoke intervention by their powerful foreign patrons, who would be siding with the fundamentalists."

The questioner's claim might be grounded in a 2013 article by journalist Seymour Hersh in the London Review of Books, which claimed the jihadist rebel group al-Nusra was behind the attack. The New Yorker and Washington Post both declined to publish the report, saying it didn't meet their standards. A follow up report from Hersh claimed the Turkish government supplied the chemical weapons for the attack.

Emails to Flynn and spokespeople for the Trump transition team were not returned.

Flynn told the Washington Post this year he was paid through his speaking agency for the appearance at the RT event. At the 2015 dinner for RT's anniversary, Flynn was seated at the same table as Putin.

Before the panel, Flynn tweeted, "Regarding RT panel participation: know my values and beliefs are mine & won't change because I'm on a different piece of geography."

At the event, Flynn cautioned the situation on the ground in Syria was complex and deception was being use.

"What I know is that the complexity of the situation on the ground right now is beyond anybody's wildest imagination," he said. "[The panel moderator] highlighted it in one of her questions. I think her question was a very good one. It's all of the things that are happening, not just in Syria. This is happening in the region in a big way. The things that you're talking about, there's this tit-for-tat or there's this give and take. People are doing things. There is deception being used."

"There is false information being used," he added. "This slide that I have up here is a component of that false information or how false information is applied. We have to understand -- this is why I think [the panel moderator is] driving me crazy up here, trying to get me to be more specific because right now we do have to be more specific. We have to be much more specific in our relationships, far more specific in our relationships, so there's not a misunderstanding and there's not a miscalculation because of some ill-advised tactic that's used in Damascus or Baghdad that causes something that we don't want."

After publication of this story, RT cut the clip and posted it on YouTube. Watch it here: