Other experts also have little doubt that China was behind this attack.
This is quoted from: http://motherboard.vice.com/read/did-china-just-launch-a-cyber-attack-on-github
When I was learning English I was told
little means very very less while
a little means some. According to the context it seems the experts were quite sure it's an attack from the China Government, then why not use
a little doubt here. What kind of meaning is the author trying to convey?