The State will deploy more than 2,500 troops to protect heads of state from potential attacks during the EU's enlargement celebrations in Dublin on May Day.
Naval vessels will patrol Dublin Bay, air force helicopters will support police on the ground and experts in chemical, biological and nuclear attacks will be on standby.
A bomb squad will be on alert throughout the day and the military will help whisk EU presidents and prime ministers to and from the enlargement ceremony, to be held in a sealed-off park on the outskirts of the city.
The Department of Defence outlined its plans for May Day in a memo. "In excess of 2,500 Defence Forces personnel will be involved in these operations," it read.
Thirty world leaders will be in Dublin on May 1st to mark the expansion of the EU from a 15 - to a 25-nation bloc, including some dignitaries from nations hoping to join in the future.
British Prime Minister Mr Tony Blair, French President Mr Jacques Chirac, German Chancellor Mr Gerhard Schroeder, Italian Prime Minister Silvio Berlusconi and Spanish leader Jose Luis Rodriguez Zapatero are all expected to attend.
The choice of date has raised fears that anarchists and leftwing extremists might hijack the occasion, turning the traditional 'day of the workers' into a violent protest against capitalism and globalisation.
The enlargement ceremony will take place in Phoenix Park, which will be closed public on May Day - a decision which protesters say is excessive.
Ms Patricia McKenna, a Green Party MEP, suggested the authorities might try to provoke violence to give themselves a pretext to take a tough line against protestors when US President George W. Bush visits Ireland in June.
"It begs the question as to whether that is part of their strategy," said Mr McKenna.