A major security operation is being mounted at Shannon Airport in advance of the arrival of the US presidential aircraft, Air Force One, in the early hours of tomorrow morning.
President Bush's plane is due to make a brief refuelling stop on its return to the US from Pakistan.
The operation is understood to involve more than 400 gardaí, Army, air corps and airport security.
Mr Bush has been on state visits to Pakistan, India and Afghanistan.
It is understood that US secret service personnel visited Shannon Airport some days in advance of a stopover by Air Force One on the outgoing leg of Mr Bush's tour to assess the security risks.
Earlier in the week, Green Party chairman John Gormley said: "There can be no doubt also that the appearance of President Bush in Shannon along with American troops, who use the airport as if it is a military complex, increases the likelihood of an attack on this country from terrorists." About 20,000 US troops each month are believed to pass through the airport en route to the war in Iraq.