Vladimir Putin clearly enjoyed his stay in the US. And why not? He caught a 30-inch striped bass, took the helm of the Bush family speedboat and was treated to lobster and swordfish amid some of North America’s finest coastal scenery. In the process he was paid the compliment, not lavished on any other leader, including Tony Blair and Hu Jintao, of 24 hours’ close personal attention from the President of the United States at his parents’ home in Kennebunkport.

“The main thing”, Mr Putin’s Foreign Minister said before the meeting, “is that the US and Russia should perceive each other as equal partners.” Mr Bush indulged this fantasy even though the US economy is 14 times larger than Russia’s and the US spends 15 times more on defence; and even though Mr Putin had the nerve two months ago to draw an egregious public parallel between US foreign policy and that of Nazi Germany. Mr Bush has shown his Russian counterpart extraordinary generosity and respect. It is time now for Mr Putin to show he deserves this indulgence.

By far the most important items on the “lobster summit” agenda were Iran’s nuclear weapons programme and the related controversy over a proposed US missile defence shield based in Europe. Moscow has hitherto supported, albeit grudgingly, two sets of UN sanctions on Tehran for refusing to suspend its uranium enrichment programme. Those sanctions have not halted the enrichment. Nor has Mr Putin been willing until now to accept the logic that flows from this failure – of preparing for a nuclear-armed Iran. His expanded offer of cooperation in building a missile shield is therefore highly significant.

When first mooted at last month’s G8 summit in Germany, this offer consisted of an invitation to use a Soviet-era radar station in Azerbaijan. Mr Putin is now suggesting “an entirely new level of cooperation” involving a brand new station in southern Russia and two European “information exchange” centres, all run by the Russia-Nato Council. This is more than calling Washington’s bluff. It amounts to a major change in Moscow’s stance, and alone makes Mr Bush’s investment in goodwill worthwhile.

Mr Putin cannot expect to dictate the structure of US missile defences simply by softening his position, however. The Pentagon’s plans to build its own early-warning radar in the Czech Republic and to base interceptor missiles in Poland are already far advanced. There is, inevitably, a political component to the choice of these locations; they will mean lucrative service contracts for the countries concerned for years to come. But, overwhelmingly, the choice is strategic. Should Iran acquire a long-range missile capability and use it to threaten the West, the best hope of an effective defence rests with interceptors based in Eastern Europe, not the Caucasus.

It can be argued that Donald Rumsfeld, the former US Defence Secretary, was insufficiently mindful of Russia’s self-esteem when announcing the Czech and Polish installations. For practical reasons it is, likewise, sensible to be savvy when building ties with former Soviet satellites such as Ukraine and Georgia. But these are independent countries. Any new alliances they may forge are ultimately for Russia to adapt to, not wreck. This is the reality that Mr Putin and his successors must accept in return for being accepted as “equals”.