The conflict in Iraq, anti-terrorism measures and combating the international AIDS crisis will be major items on the agenda during the US-EU summit in Ireland this month, which is being attended by President Bush.
The American ambassador to Ireland, Mr James C Kenny, said yesterday it was "hugely important to the United States that that summit has some great successes", describing as "indispensable" the relationship between the US and Europe.
"Our relationship is indispensable because no matter how much we may disagree on the detail, we do agree and unite in purpose."
He said the Irish presidency had done "an outstanding job" trying to fortify the ties that existed between the US and the EU, and he was confident that both the US and the EU would "advance our agendas" on a range of issues at the summit, expected to take place in Dromoland Castle near Shannon Airport.
He said Iraq, counter-terrorism, economic growth and non-proliferation would be key areas of discussion between Mr Bush and Mr Ahern.
Mr Kenny expected the summit would also make advances on enhanced co-operation against the spread of HIV/AIDS, "an issue given special focus by the Irish presidency".
He said the US was Europe's "strongest ally", supporting European integration and the NATO alliance.
Co-operation between both was essential because of the threat of terrorism, he said, defending US policy in relation to the threat.
"We did not seek this war on terror, I want you to know, but at the end we must prevail here. America and Europe must make the effort, and we have done so. I give the examples of taking down the Taliban, cutting off terrorist funding, arresting and disrupting terrorist cells that were planning attacks here in Europe and in the United States."
He said that if this failed democracy would be at risk. "And right now we cannot fail in Iraq, regardless of whether or not you agree with the rationale for military action."
Mr Kenny made his comments at the publication of a book of essays on EU-US relations from an Irish perspective, called An Indispensable Partnership, and edited by former Irish Times journalist Joe Carroll and economic consultant Mr John Travers.
In the book, the Minister for Foreign Affairs, Mr Cowen, said that while the Iraq issue "defined the recent low point in transatlantic relations", the present situation proved that "EU-US relations are indispensable".
He said stability in Iraq could not be achieved by the US and its coalition partners alone, and the new UN Security Council resolution "should provide the basis for restoring international consensus and co-operation".
However, he believed it was "not possible or desirable" that the EU should seek to emulate the military superiority of the US. EU foreign policy should focus on "conflict prevention strategies" as opposed to "pre-emptive military action".