From NBC News:
Drawing parallels with Western support for anti-Soviet fighters in Afghanistan in the 1980s, some of whom later formed the al Qaeda organization which attacked the United States in September 2011, Assad said Washington and Europe would regret supporting rebels in Syria.
"The West paid heavily for funding al Qaeda in its early stages in Afghanistan. Today it is supporting it in Syria, Libya and other places, and will pay a heavy price later in the heart of Europe and the United States," he told al-Ikhbariya channel.
"The truth is, what is happening is that we are mainly facing extremist forces," Assad added.
He was speaking a week after Syria's rebel al-Nusra Front, one of the most effective rebel forces battling his troops, formally pledged allegiance to al Qaeda leader Ayman al-Zawahri.