Five cables cut: what's happening under the seas?

What's going on under the seas? Five undersea communication cables have been cut in the past two weeks, two near Alexandria in the Mediterranean, two in the Persian Gulf, and one near Malaysia (see map below, from Engadget).

Internet data (which is mostly carried, long-distance, via undersea cables), voice calls and video traffic were all disrupted, affecting tens of millions of people (at a certain point, rumors went around that Iran was cut off from the Internet, which was/is not true). The first occurrences were attributed to ship anchor's dragging, but the Egyptian government dismissed that. There are no reports so far of intentional sabotage, but five cables severed within a few days seem more than a coincidence and do raise questions and suspicions.

Khaleej Times and the IHT have detailed stories, security expert Bruce Schneier is tracking the developments, and Steve Bellovin at Columbia is analyzing them.