The perceived threat of a tiny fishing boat has now turned into a huge embarrassment for the US navy here in the Gulf.

As soon as news of the shooting broke on Monday afternoon, the navy said the USNS Rappahannock's crew had issued warnings to the approaching fishing boat - warnings which they said were not heeded, leading them to open fire with a .50 calibre machine gun.

They killed one Indian sailor and injured three others.

More embarrassing however, is the bold challenge against the navy's account of the incident.

“They were given no warning,” MK Lokesh, the Indian ambassador to the UAE, told me by telephone, a statement reverberating around news outlets for most of today.

The surviving sailors have told reporters the same thing.

But the ambassador also said the navy ship did not stop when it recognised the mistake, or offer any assistance to the bullet-riddled boat.

“They didn't come to the aid of the people,” he said. “They sailed off.”

The Straits of Hormuz are regularly a playground these days of tense stand-offs and threats as sabre-rattling has replaced diplomacy between Iran and the US on the use of the vital waterway.

However, Monday's shooting happened around 15km off Jebel Ali Port, well over 200km from the Straits, inside the Persian Gulf.

Investigations have been demanded, reports have been promised, and UAE, American and Indian authorities are all openly discussing a search for the truth in the coming days.

But when it comes to defence issues in the Gulf's waters right now, few things could be more sensitive, and getting real answers is unlikely.

The four Indian fishermen were reported to have been on a small 9m skiff.

The USNS Rappahannock is over 180m long.

Regardless of the tension in these waters, the image of such giant, machine-gunning fishermen returning home with their catch will be difficult to explain away.