This article from Cult of the Mac report on the legality of the US Government to access data from non-us citizen on any US based Cloud-type storage services (not just iCloud as mentioned in the title) without a warrant. This does means DropBox, Google Drive, iCloud and so on.
Read the original post here: U.S. Authorities Can Access Non-Citizen iCloud Data Without A Warrant [Updated] | Cult of Mac.
Check the french company OVH and the solution called “Hubic”, not yet faster than dropbox, but outside the US patriot-act control.