As Syria's vicious civil war enters its fifth year, President Bashar al-Assad granted CBS News a rare one-on-one interview, a year-and-a-half after his last conversation with "CBS This Morning" co-host Charlie Rose. Their meeting Thursday in Damascus came after reports of a new chlorine gas attack that allegedly killed six people.

Assad pushed back against claims his regime is using chlorine gas, and the devastating and equally indiscriminate barrel bombs which are dropped from helicopters.

"This is part of the malicious propaganda against Syria. First of all, the chlorine gas is not military gas. You can buy it anywhere," Assad said, suggesting if anyone had used it, it was the rebels trying to oust him.

He said even they don't use it often because it's "not very effective."

"It's not used as military gas. That's very self-evident. Traditional arms is more important than chlorine, and if it was very effective, the terrorists would have used it on a larger scale," Assad said.

Rose asked why Assad then does not allow international inspectors in to verify whether the poison has been been used or not.

"We would," Assad said. "We always ask the delegation, in parts delegation to come and investigate. But I mean, logically and realistically it cannot be used as military. This is part of this propaganda because, as you know, in the media, when it bleeds it leads... and they always look for something that bleeds, which is the chlorine gas and the barrel bombs."

According to the Syrian Observatory for Human Rights, over 200,000 people have been killed in the civil war in Syria, and more than 85 percent of the civilians who have died have been killed by government forces.

Assad rejected the figures.

"As I said earlier, the war, it's not about -- it's not traditionally war. It's not about capturing land and gaining land. It's about winning the hearts and minds of the Syrian. We cannot win the heart and minds of the Syrians while we are killing Syrians," Assad said.

"We cannot sustain four years in that position as a government, and me as president, while the rest of the world, most of the world, the great powers, the regional power, are against me and my people are against me," he added. "That's impossible... So this is not realistic and this is against our interests as government is to kill the people. What do we get? What the benefit of killing the people?"

The interview was shot by Syrian TV at the request of Assad's people, citing "security" reasons. However, nothing was off-limits when it came to Rose's questions.

You can watch more of Charlie Rose's interview Sunday on "60 Minutes." Check your local listings.