They didn't know about the pipeline? Or you are saying they didn't know about the explosion?

Neither makes any sense at all. Of course they aren't going to admit to it.

They absolutely did have the technology to do it, again read the link. They have a ship with seabed mapping and drones for attaching explosives to mines. It's the perfect ship to do the job.

You somehow think the Seals are behind every curtain, but the obvious answer here is the poles.