The Minister for Transport will give a response in the coming days to a letter from SIPTU seeking clarification on the proposed break-up of Aer Rianta.
His response will decide whether the union, which represents about 70 per cent of Aer Rianta workers, will go ahead with industrial action next week.
SIPTU members at the State-owned airport operator will stop work for two hours next Thursday at Dublin, Cork and Shannon airports if they are dissatisfied with Mr Brennan's response to nine points of clarification sought by union general secretary, Mr Jack O'Connor.
The work-stoppage coincides with the arrival of EU Justice and home affairs ministers in Dublin for a high-level conference.
SIPTU national industrial secretary, Mr Michael Halpenny said the action arose "from the ongoing failure of Aer Rianta and the Department of Transport to confirm reasonable guarantees on jobs, terms and conditions of employment and pensions".
Industrial action will be escalated during the EU presidency if the matter is not resolved, he added. Aer Rianta estimate as many 57 flights and 7,000 passengers could affected by Thursday's planned stoppage.
Speaking in Strasbourg this afternoon, the Taoiseach Mr Ahern condemned the strike-threat saying the targeting of EU meetings was an imported bad habit.
Meanwhile, CIE workers are threatening industrial action to coincide with Aer Rianta's stoppage. They are also concerned at plans to break their company three separate parts.