The DC-10 jet, operated by Omni Air International under contract to the US Air Mobility Command, was targeted in the early hours of December 20.
Gardaí and airport authorities have been left baffled by the incident with no claim of responsibility from any group.
Local anti-war groups claimed to have had no knowledge of the planned attack or who carried it out. Damage to the aircraft was discovered at around lunchtime on December 20. An anti-war slogan had been sprayed on the aeroplane while hydraulic lines were also damaged.
There had been no claim of responsibility from anyone until yesterday when the Galway Alliance Against War monthly bulletin reproduced the content of a “handwritten communication we received from one of the members of the peace team that sabotaged a US troop transporter at Shannon warport”.
The alliance said it had verified that the person who sent the letter took part in the action. According to the letter: “It was appropriate to carry out this peace action in Christmas week, when the media and politicians’ speeches, the world over, are full of hypocritical Christian cant about peace, while they support and even profit from wars in far off lands.”
The letter outlines how the unnamed group was dropped off at a perimeter fence to “Shannon’s warport” and how it quickly cut through two fences to enter the airfield.
The letter goes on to describe how the people made their way towards the target plane.
“Although there was plenty of activity at the terminal, the area around the plane was completely deserted. Actually, we all lay on the ground observing the plane and its surroundings before we decided to move in and carry out our act of sabotage,” the letter claims.
“Beforehand we agreed we would immobilise the hydraulics of all the landing gear. Four sets of landing gear were sabotaged. This was all pre-planned. Another peace activist sprayed the words: ‘Peace — US troops out’ on the side of the plane.”
A Garda spokesman confirmed that the investigation is continuing.
US military planes at Shannon Airport have been attacked before.
In January 2003, activist Mary Kelly attacked a US navy jet at Shannon with an axe. Her conviction was quashed earlier this year.
Days after that incident, a group of five activists damaged the same plane after it had been moved to a hangar for repairs. Following a 21-day trial in 2006 the five were acquitted.