No, we don't. This article is a hit piece... They focus on the one case where the intel community chose to tap hubs in the US, which is domestic surveillance and requires a warrant, as it always has and should since espionage agencies are forbidden by numerous laws from collecting domestic intelligence. Why they did not choose to monitor transmissions locally or alternately through one of our allies (Britain) hubs as is typically done in such situations is the question that should be focused on, but is instead totally avoided.
The Pentagon lawyers who failed to lie (possibly the only time in their lives they didn't) should quickly commit seppuku.
No warrants are needed for combat surveillance, not in the US, not in Iraq, not anywhere we have a livefire, hot LZ (even if the law can be read to require them).
Why should we have to worry about a warrant for messages or calls that are from a foreign source to a foreign source which happen to route electronically through a domestic US hub or server?