(CNN) As the plumes rise from a brazen attack in the Gulf of Oman, oil brokers and diplomats are panicking about another lurch toward confrontation In the Middle East.

What happened is fairly clear -- two tankers were struck as they sailed through this busy and strategic shipping lane -- but why it happened and who did it is a lot less easy to explain, not least because it doesn't appear to benefit any of the protagonists in the region.

The Japanese-owned Kokuka Corageous tanker briefly caught fire when it was twice attacked with "some kind of shell," its owner said. One of its 21-strong Filipino crew was injured.

The crew of the Bermuda-based Front Altair all escaped unharmed when it too was hit by a blast. The US Fifth Fleet's destroyer USS Bainbridge was nearby and responded to a distress call received at 6:12 a.m. local time and then another 48 minutes later. It picked up 21 sailors from the Kokuka and is getting a wider view of the scene from a P-8 Navy surveillance aircraft.

A tanker ablaze in the Gulf of Oman, in an unverified image supplied by an Iranian news agency.

With the rescue operation over, questions have turned to why anyone would do this. That's not as not as straightforward to answer as it looks.

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