No US military aircraft has landed at Baldonnel since the summer of 2002, although foreign aircraft occasionally use the facilities there, the Taoiseach told the Dáil.
Mr Ahern said that permission for the landing of foreign military aircraft at Baldonnel was granted subject to the usual stipulations: that the aircraft was unarmed and carried no ammunition, explosives or intelligence-gathering equipment.
"There have been no landings, or requests for them, at Baldonnel since the present US military movements began in the autumn of 2002," he told the Fine Gael leader, Mr Enda Kenny, who had referred to weekend speculation that Baldonnel was now also being used for US military flights in addition to Shannon.
Mr Ahern said his latest information relating to military aircraft at Shannon was that a very limited number of US Air Force planes were currently using the facilities there.
"I understand that US authorities do not anticipate any significant increase in the number of planes using Shannon in the period ahead. A few days' notice is usually given in these cases, so we have not been given any indications as yet of any further use of the airport," the Taoiseach said.
"Obviously, a proportion of the civilian aircraft carrying additional US troops to be deployed in the Gulf may land at Shannon, but the usual rules would apply in such cases, and they must inform us as such."
Mr Ahern added that civilian aircraft chartered by the US military sometimes transported personal weapons and ammunition over Ireland, but permission for such flights must be sought from the Minister for Transport.
"However, there is no question of large-scale weaponry being routed to Iraq over Irish sovereign space. The US does not use our air space for that."
Mr Kenny said he had been informed that, on one night 10 days ago, 63 overflights took place at 65,000 feet. A court action was due regarding the legitimacy of offering the US the use of facilities at Shannon, and the Taoiseach had been at pains to point out that Ireland was not a participant in the war, he added.
Mr Kenny raised the matter of military personnel who had passed through Shannon and might have been victims of the suicide-bombing in Iraq some days ago, or involved in the deaths of civilians at Basra.
He asked: "Does that not constitute assistance to the provision of facilities for the war effort ? Does it not mean the Taoiseach's claim of non-participation in the war and non-contribution to the US war effort is invalid?"
Mr Ahern replied that it did not. "Under our law, it is quite clear that US use of facilities at Shannon does not constitute participation on our part. That has been the position down through generations.
"I know that people continue to raise this issue, but the international legal position is that we are not participants in the war. We have provided facilities at Shannon to many different countries since 1955."
