Sorry for a late showing, but I read Hersh's claims with some interest and just wanted to point out a few things which, I would have thought such a seasoned journalist probably should have double checked prior to publication.
The US used C4 explosive and Hersh mentions 'C4' seven times, and suggests they were used to fabricate shaped charges with a concrete housing.
1. C4 is a plastic explosive with 9% of its composition being plasticisers, binders and storage preservatives, and as such is unsuitable for demolitions at depth due to exudation of the material causing separation and micro air pockets being effected by Boyle's Law.
2. C4 contains a chemical tag which can trace it back to place of manufacture and batch number.
3. Undersea explosives are almost exclusively in a cast form such as Torpex, Amatol or RBX polymer that are solid when formed, negating any need for a concrete housing.
4. A shaped charge would almost always need a metal liner for the cutting elements, which again is an unnecessary piece of traceable evidence to examine and assign to a potential perpetrator.
5. Soviet, Iranian, Chinese, North Korean sea mines or undersea explosives are all in the possession of both the UK and US and (my assertion) is that if the US were to commit a deniable act of sabotage to an allied country's infrastructure, I imagine they would use devices that would steer the evidence away from them.
The US Air Force wanted to use an air dropped weapon to attack the pipeline: "The Air Force discussed dropping bombs with delayed fuses that could be set off remotely."
1. I am unaware of any bombing fuze that is designed to be remotely detonated at a later date by a third party.
2. I am unaware of any easy way to remotely detonate any air dropped weapon fuze through 260' of water.
3. I am unaware of any air dropped weapon that has both the aerodynamic and hydrodynamic characteristics to be dropped accurately onto a static target underneath 260' of water. I suppose an aerial torpedo could theoretically be used, but these detonate on contact with the target as opposed to sitting awaiting a command to detonate.
The charge was detonated by a sonar buoy dropped from an aircraft.
1. Sonar signals would be like RF hazards in dry land demolitions and AFAIK the Baltic Sea is full of uncontrolled sonar emissions which would be a risk to the remote-detonation assertion. I have to admit I am no expert on sonar.
Mixed Air diver's were used to place the explosives on the pipeline.
1. Mixed air diving requires a lot of infrastructure to support, including diving bells, decompression chambers and casevac capabilities.
2. It seems unnecessarily James Bond-esqe when an unmanned underwater remote vehicle could attach the charge to the pipeline with much reduced risk to personnel and reduced infrastructure requirements.
The US divers operated from Alta class Norwegian Mine Sweepers.
1. The Alta, Orkla and Glomma were all scrapped or destroyed prior to the attack, leaving only the Otra and Rauma in service and they have been accounted for during the time they were supposedly dropping US divers into the Baltic Sea.
Jens Stoltenberg, a Norwegian, secretly colluded with the US since the Vietnam War.
"Today, the secretary general of NATO is Jens Stoltenberg, a committed anti-communist, who served as Norway’s prime minister for eight years before moving to his high NATO post, with American backing, in 2014. He was a hardliner on all things Putin and Russia who had cooperated with the American intelligence community since the Vietnam War. He has been trusted completely since. “He is the glove that fits the American hand,” the source said."
1. Stoltenberg was 16 years old when the Vietnam War ended and was still a student at the Oslo Catholic School, after which he performed his National Service in the Infantry prior to getting a degree in economics in economics from the University of Oslo in 1987. He also appeared to be very anti-US policy in Vietnam in his youth, which seems at odds with being some kind of youthful intelligence asset of the US.
Wikipedia: "Stoltenberg's first steps into politics came in his early teens, when he was influenced by his sister Camilla, who at the time was a member of the then Marxist–Leninist group Red Youth. Opposition to the Vietnam War was his triggering motivation. Following heavy bombing raids against the North Vietnamese port city of Hai Phong at the end of the Vietnam War, he participated in protest rallies targeting the United States Embassy in Oslo. On at least one occasion embassy windows were broken by stone-throwing protesters."
It would take some deep game theory to believe that Stoltenberg was a US intelligence asset in his youth from Catholic School and college to enhance his deep cover by attacking the US Embassy in Normay.
This was a joint US-Norwegian act of sabotage against Germany, a NATO ally and trade partner with both the US and Norway:
This is my opinion, but all covert military operations are considered with what the effects of it going wrong are, and the idea that the US and the notoriously-compliant-to-international-law Norwegians would act against Germany, to me, is absurd. The risks do not in anyway balance with any possible reward. The US relies on German intelligence as well as most European countries to have a trusting relationship with, and blowing up a pipeline is just not enough of a prospect to risk that.
In short, Hersh's article is nonsense, and the entirety of the evidence he presents is summarised as 'some guy told me' hearsay.