The Department of Foreign Affairs has insisted that training exercises by US military aircraft over the southern Irish coast in recent days have no implications for neutrality.
A Department spokeswoman said the exercises by two C-1 Hercules transport planes flying from Shannon Airport were "purely for routine training purposes" and the aircraft have now left Irish airspace.
"The Department does not see this as having implications for Irish neutrality," she said.
The spokeswoman said the US Air Force aircraft used in the exercise had no intelligence or surveillance equipment on board. "This was a routine training exercise, and the Irish Government gave it full permission," she added.
She could not confirm whether it was the first time the US military has been involved in aircraft training exercises in Ireland.
However, the Green Party's foreign affairs spokesman, Mr John Gormley, said last night that the development was "extremely worrying, but it shouldn't surprise us unduly given this Government's record on foreign policy. It shows that we are totally and utterly in hock to the US as far as foreign policy is concerned."
Mr Gormley said he was not comforted by the Department's assurances that the exercises had no implications for neutrality.
He said: "Nothing has any implications for neutrality, and the only way that they define neutrality is that we are not part of a military alliance. Everything else goes."
Mr Gormley said that, based on such a definition, the Government's proposed declaration safeguarding neutrality in a revised Nice referendum this year was "absolutely meaningless".
The aircraft are understood to have been using Shannon Airport for pilot training, involving take-off and landing exercises and basic manoeuvres. The C1 Hercules planes, also known as C130-Ks, are four-engine aircraft often used to transport troops or stores.
The Government came in for criticism last September when it offered the US Air Force the use of Irish airports and airspace in the wake of the terrorist attacks on the World Trade Centre and the Pentagon. Shannon Airport was used during the Gulf War as a staging post for US military shipments.