To eavesdrop on the security debate between the US and its European allies is to hear two sides talking, sometimes shouting, past each other. Here are issues of life and death, decisions to determine how the world can be made safe for our children. Yet the transatlantic conversation is mired in mutual misunderstanding.

We always knew that the Nato alliance could not escape the consequences of the passing of the cold war. A strategy to constrain the Soviet nuclear menace would not survive the emergence of the US as the single superpower.

Thus far there has been no great ruction. Squabbles have been patched up, differences papered over in the formulation of the alliance's new strategic doctrine. The fractures, though, are becoming visible. Two damaging disputes loom: over US plans to build a shield against nuclear attack and over Europe's hopes for its own defence capability. More than that, it is ever clearer that the US and Europe look out on to different worlds.

For Europeans, the US seems an impregnable fortress. Economic might, advanced technology and geography make it invincible. Its sophisticated weaponry is 15, maybe 25, years ahead of any potential rival. Before too long it will have the capacity to fight wars by remote control. If there is a single chink in its armour, it lies in the reluctance of its leaders to accept that war will always involve some casualties.

Now look through Washington's end of the telescope. Hegemony, it seems, brings its own vulnerabilities. Sure, the risk of a Russian nuclear strike is now as close as it gets to zero. But in the US mindset, the old cold war certainty of Mutually Assured Destruction has been replaced by new, less calculable dangers.

America's very power makes it the target for rogue states and terrorists. The Pax Americana has many enemies. Start with North Korea, Libya, Iraq, Iran. Washington sees a world of loose nukes, lethal bugs and deadly chemicals. The profileration of ballistic missile technology promises to give its foes the means of delivering these weapons of mass destruction to US soil.

This threat is as real to Americans as it seems remote to most Europeans. There is something else. US leaders believe they have both the duty and, most importantly, the capacity to eliminate it. Victory over communism has been followed by the triumph of US liberal capitalism. The US has the means - the wealth and the technology - to live in a risk-free world.

I exaggerate somewhat here. But not much. The US project to build a National Missile Defence (NMD) - all but certain to be given the go-ahead this summer - unites together these two conflicting threads of intense insecurity and brash self-confidence.

It is not enough that the US can launch massive pre-emptive strikes against potential adversaries. Nor that it can deter any attack by promising to eviscerate those responsible. It must innoculate itself against all threats. To the familiar strategic doctrines of pre-emption and deterrence, Washington now adds that of "futility": America's enemies must understand that any attack on its territory would be a futile as well as a fatal gesture.

Here the transatlantic gulf opens. Europeans cannot contemplate living in this world without risk. The so-called rogue states of the Middle East are on its borders. So too are the Balkans and, beyond, a Russia which, for all that it is impoverished, remains the world's second nuclear power. Money and technology cannot remake geography; even if they could, Europe matches America in neither.

The disquiet runs deeper. Seen from Europe's side of the Atlantic, making America safe will inevitably make the world more dangerous for its allies. Abrogating the 1972 Anti-Ballistic Missile Treaty would make Russia feel more threatened. It would remove too the remaining, flimsy restraints on nuclear proliferation.

Unsurprisingly, Russia refuses to accept that the US intends to spend tens of billions of dollars building defences against the one-in- a-million chance of a lone missile fired by, say, North Korea. Americans are not that stupid, one European foreign minister visiting Moscow was recently told by his Russian hosts.

So if the US builds missile defences, Russia will respond with more sophisticated counter-measures. So too will China. In Beijing's eyes, NMD has sinister implications. It might embolden a US-defended Taiwan to declare independence. Safe behind its shield the US could threaten a first strike in the confidence that it could neutralise any retaliation.

NMD also decouples US from European security. For decades, the Nato allies sheltered under the same umbrella. Deterrence doctrine was built on the presumption of shared vulnerability. Washington was as much at risk as Bonn or Paris.

A shield around the US up-ends that balance. If there is a significant threat from so-called rogue states, Europe becomes the obvious target - and its own strategic defences are undermined. After all, if the US, with all those thousands of missiles, has decided that deterrence is not enough, what purpose is served by the much smaller British and French nuclear forces?

Washington offers answers to these questions. After a long period of silence, the US has recently circulated a series of papers to its allies on threat assessment and deterrence. There is an implicit rebuke to the Europeans for failing to take seriously enough the proliferation of weapons of mass destruction. Also the assertion that NMD is good for Europe as well as the US: with their own security enhanced, Americans would be more rather than less willing to come to the aid of its friends.

These are theoretical debates which can never be definitively settled. Suffice it to say that the Europeans are pretty scornful of such assurances. Yet they are also resigned to the prospect that the US will press ahead.

Tony Blair has indicated informally that Britain will permit the necessary upgrading by the US of the Fylingdales radar station in Yorkshire. He could hardly do otherwise. Britain will have to start thinking soon about a replacement for its own Trident nuclear missile system. That makes it entirely beholden to the US.

Other European governments talk of damage limitation: might Russia be persuaded to amend the ABM treaty in return for American guarantees that the scope of NMD will be severely restricted?

Behind all this, though, lies the earnest hope in Europe that the technology will fail, that NMD simply won't work. Extraordinary, when you think about it. Here is a project which the US sees as central to its security and yet its Nato allies are willing it to fail. That's what happens when friends talk past each other.

Financial Times (London)
April 14, 2000.