Azure Backup and site-to-site VPN

Hi,

We are looking at using Azure Backup with DPM 2012, and also looking at implementing a site-to-site VPN from our network to Azure.  I am supposing that the traffic from DPM to the Backup Vault in Azure is going to travel over our general Internet connection and not use our site-to-site VPN; is this true?  If so, is there a configuration option to direct the DPM-to-Backup-Vault traffic through our site-to-site VPN?

thanks!

Martin