As President Bush goes to Europe, expect Europeans to welcome him cordially and show good will, but don’t expect them to agree. With elections in Iraq successfully completed and a new mood of optimism between Israel and the Palestinians, Europeans are making the right noises. Secretary of State Rice’s European tour was a success. But don’t be fooled. Not all is well in trans-Atlantic relations, and this hopeful moment is not destined to last. Even as tensions peaked, few on either side of the Atlantic doubted that trans-Atlantic relations were built on shared interests no less than shared values. America understands that it is better to have Europe on its side than on the side. Europe understands that, after Mr. Bush’s triumph in November, it must cooperate with him. But good will is no substitute for policy, and interests are not as shared as they might have been in the past. The current lull is due to a momentary convergence of positive events.

Europe’s euphoria on the Palestinian-Israeli front underscores a failure to appreciate that regional trouble lies east, not west of the Jordan River. And although conditions for Israeli-Palestinian detente are less bleak than at any point in the last four years, optimism relies only on a handshake and a fragile ceasefire. One successful terror attack would suffice to stall progress. America’s caution underscores awareness of how fragile this moment is. Europe’s enthusiasm indicates a lack of appreciation for the challenges ahead. The gap on final status issues remains considerable. It will be difficult enough to maintain the ceasefire and ensure a successful and peaceful Israeli disengagement from Gaza without major repercussions at the leadership level. Rushing to final status is overkill. Yet, that is Europe’s hope, because it fails to appreciate what brought this moment and how fragile circumstances are for progress.

Unlike America, Europe still fails to recognize that Palestinian intransigence torpedoed all recent peace efforts and that Prime Minister Sharon’s use of force, not European mediation, defeated the so-called second intifada. Having backed Yasser Arafat for too long, all that Europe grudgingly acknowledges is that Arafat’s death was helpful. When negotiations stall on refugees, Jerusalem, borders, and settlements, Europe’s failure to read the map correctly will cause it to blame Israel and America yet again.

But the peace process is just a sideshow compared to potential disagreements over China and Iran. A crisis over China is already in the making. Iran will follow, degenerating into a contest as acrimonious as the one over Iraq.

This trans-Atlantic moment will turn sour because divergences over interests underscore a broader point: these are not the causes of the trans-Atlantic crisis, but its symptoms. The underlying cause is a profoundly different normative worldview that dictates different policy approaches to shared challenges on both sides of the Atlantic, one that will drive the two sides further away.

Take China. With all its posturing as a new global superpower committed to human rights, Europe will not heed American demands that it keep its arms embargo on China. Europe’s only interest in China is commercial. A two-way trade worth $173 billion in 2003 and growing is a convincing argument against the embargo for the Europeans, human rights notwithstanding. Europe believes that engagement, dialogue, and commercial ties will ultimately redeem human rights. But if Europe is wrong and China starts a war against Taiwan, an American fleet, not an imposing European one, will protect China’s only democracy against an expansionist, communist regime.

On Iran, all agree that a nuclear Iran is a threat to regional stability. But Europe resents America’s refusal to “engage” Teheran and offer political dialogue, diplomatic detente, and trade. While America believes that diplomatic carrots occasionally need a big stick to persuade, Europe believes only in carrots – and has few sticks. Europe has no intention to back its diplomacy with credible threats. Britain’s foreign secretary, Jack Straw, said violence would be “unimaginable.” And loss of lucrative contracts will act as a powerful deterrent against economic sanctions.

For now, Washington is happy to let France, Germany, and Britain – nicknamed the EU-3 – try to persuade Tehran to forgo its nuclear program. But patience will run out. Iran is only buying time. As happened over Iraq, Europe’s unwillingness to see reality for what it is – a rogue state posing a long-term threat to regional stability and exploiting Western divisions to its own advantage – is becoming an impediment.

When talks fail, Europe will blame America for not having joined the EU-3, not having engaged the Iranians, not having adopted a more conciliatory tone. With little left to do aside from tough measures, a new showdown will occur between Europe, with its resolve never to use force, and America, with its impatience with Europe’s penchant for appeasement.

Therefore, enjoy this cordial moment. It will not last forever.

Mr. Ottolenghi teaches Israel studies at Oxford University. He is a visiting scholar at the American Enterprise Institute.