NIST, the American National Institute for Standardisation and Technology, is a pioneer in providing Cloud-guidance. Their definition of Cloud is widely used and commonly accepted as the only valid definition of Cloud services.
Earlier versions of NIST documents stated that a cloud service must be provided through public internet connections. The recent development of network-operators providing dedicated connections between cloud service providers and cloud users most likely influenced NIST in removing the requirement of delivery through public internet connections.
Publications by NIST: