'Relaxed", "constructive", "positive". These were words used to describe the recent EU-US summit at Dromoland Castle in Co Clare. They were a very necessary antidote to the negativity generated around the relationship over the previous three years.
We were at risk of losing sight of the fundamental convergence of interests and values across the Atlantic. Not only do we share a fundamental respect for democracy and the rule of law, but our economies are inextricably tied up with one another.
Twelve million jobs on both sides of the Atlantic depend on investments from Europe in the United States or vice versa. Europe and the United States together are half of the entire world economy. US investment in Germany alone exceeds all its investments in Latin America. Europe provides half of all the external earnings of US companies, and the United States provides an even bigger share of the external earnings of EU companies.
In its fight against terrorism and international crime, the United States has an essential ally in the European Union. In response to 9/11, the EU has introduced a common arrest warrant for certain trans-border crimes (including terrorism) and is introducing sharing of intelligence and common approaches to criminal law and procedure.
Thus the US finds its task in dealing with international terror and crime much simplified, because on many issues it can deal with one entity rather than have to make 25 different arrangements with 25 different EU states.
An agreed approach between the EU and the US has enabled a succession of world trade rounds under the WTO to take place. The single market created by the existence of the European Union is of benefit to US companies selling in Europe, just as it is to native European companies.
Keeping all this is mind, we have to recognise that there are important areas where the EU and US have yet to find common ground. Of most lasting significance is global warming. The United States emits 25 per cent of the world's greenhouse gas with only 4 per cent of the world's population. Europe also emits more than its fair share. The notion of an effective action against global warming, without the United States committed and involved, is difficult to envisage.
The climate-change issue reveals an important general difference in attitude. The US believes a relatively painless scientific fix for global warming will eventually be found, while Europeans are much more pessimistic about this, as they are about scientific innovation in general.
The division over Iraq has also shown that more work must be done by Europe and the US on the question of how and when force might be used to intervene in the territory of another state to combat genocide, mass terrorism, weapons proliferation or humanitarian disasters. In the past, war was only considered to be justified where there had been actual aggression.
But the world has now become so interdependent that new understandings and definitions seem to be needed, and this should be a joint task. The United Nations can only do its job efficiently and speedily if there are shared concepts in regard to the justification and procedures for the use of force. This has to be done in a world where weapons of mass destruction are in the hands of an increasing number of states, and may even fall into the hands of entities that are accountable to no state.
Europe and the US also need to work together on common responses to the emergence of China and India as economic giants, on finding a solution to the conflict in the Middle East and on relations with Islam. Together the US and the EU can have a constructive influence. Separately, their role is more likely just to be one of trying to stop things.
Another looming problem is the size of the US current account deficit. These major imbalances must be rectified if the world's economy is to be sustained, and it is important that this be done within a framework of mutually agreed rules, and in a gradual fashion that does not damage business confidence.
Reaching agreement will not always be easy. Some of the negative things that kept western Europe and the US working in harness have thankfully been removed. During the Cold War, the Soviet threat provided a glue for the EU-US relationship which kept it together despite differences over Suez, Vietnam and colonial questions. That glue must now be replaced with a new adhesive based on a more positive mutual understanding of the depth of our common interest.
It is also important that United States public opinion understands the unprecedented and revolutionary nature of what the European Union is attempting to do. Virtually every state or federation that came into being in the world today, including both Ireland and the United States, did so by way of a war or a succession of wars.
In building this European Union, 25 states are now attempting to build a political entity, through which they will share some of their sovereignty, by entirely voluntary and peaceful methods.
This is something without precedent in the world, and it is important that the United States should understand this, understand the difficulties it entails, and be both patient and supportive in its attitude to European integration. As John Hume said, the building of the European Union is the world's biggest and most successful peace process.
Indeed the US should take its share of the credit for the very existence of the European Union, because it was the wise strictures in favour of European co-operation, imposed by the US as conditions for the receipt of Marshall aid in the 1940s, that started the ball rolling.
• John Bruton has been nominated as EU ambassador to the United States