The European Union must work "collectively" if terrorist outrages are to be stopped in member-states, the Taoiseach, Mr Ahern, has warned following a meeting with President Bush.
The Government is to present a series of proposals to boost security co-operation amongst the 15 EU countries and the 10 countries joining in May when EU justice ministers meet in Madrid on Friday.
The repercussions of the Madrid atrocity will also dominate the meeting in Brussels next week of EU leaders, including Mr Ahern, who is currently president of the EU Council.
"I will put forward a declaration and suggestions about things that we should do immediately," said Mr Ahern, following a White House meeting with President Bush.
Following a presentation of a St Patrick's Day bowl of shamrock, Mr Bush said Ireland and the United States are "fighting terrorism, a danger that has brought destruction and grief to Americans and Irish alike, and to the world".
In his remarks, the Taoiseach said the EU and the US "share a common determination to overcome the evils of terrorism" following "the wilful destruction of life" in Madrid.
"Terrorism is an affront to our democracies. It strikes at the heart of all of the values on which the United States and the European Union are founded," he said.
Offering sympathies once more to the families of the Spanish victims and those wounded, Mr Ahern went on: "We are determined to ensure that our peoples are protected from this despicable scourge."
Questioned about the defeat of the outgoing Spanish government following the bombings, the Taoiseach said its decision to blame Eta rather than al-Qaeda "had created some difficulties".
Downplaying fears that the Spanish Socialist Party's victory could lead to further EU/US rifts, Mr Ahern emphasised that the two must now work in co-operation.
"I think the reality is that people have believed for some considerable time that there is a danger in some European cities of terrorist attacks.
"We will have to work together to make sure that we co-operate as best we can," he said.
Though the Madrid bombing featured prominently during yesterday's talks between Mr Ahern and Mr Bush, the two men spent "a great deal of time" reviewing difficulties in Iraq, Iran and the Middle East.
Mr Bush also said he was looking forward to visiting Ireland for the EU-US summit in June.
The final shape of the package to go before EU justice ministers on Friday may not become clear until the European Commission presents its own proposals to EU member-states tomorrow in Brussels.
Adopting a security strategy last December, the EU identified terrorism as one of the key threats now facing the Union and agreed to accelerate efforts to boost co-operation.
Next week, Mr Ahern will call on all EU states to sign up to a solidarity clause guaranteeing aid to each other in the event of attack by al-Qaeda, or other terrorist organisations.
The Irish proposals, worked out over months of negotiations with other EU states, will also include the appointment of an EU security chief to boost further co-operation between EU bodies and non-EU countries.
The Government has already identified the need for measures to improve contacts between police and intelligence services throughout the EU, which are notoriously given to infighting.
However, some quarters oppose the creation of new EU bodies and instead push for an expansion of Europol's role, and greater use of Eurojust - the body set up to improve links between EU prosecutors.
Questioned about the new Spanish government's threat to withdraw its soldiers from Iraq unless the United Nations takes command there before June, Mr Ahern said the United States wanted a greater UN role.
"There were differences last year. Let's be clear about that. But there aren't differences now about moving on to see a democratic Iraqi administration. Obviously whatever the EU can do to help, we will," said the Taoiseach.
