AMERICA has the “moral responsibility” to lead a campaign to rid the world of all nuclear weapons, Barack Obama told a cheering crowd in Prague on Sunday April 5th. He offered the world a goal of eradicating nuclear weapons, although he admitted that it might not be achieved in his lifetime.

Two decades earlier, in the Velvet revolution of 1989, Czechs brought down a nuclear-armed empire without a shot, Mr Obama told an audience of some 20,000 people who had gathered in the shadow of Prague castle. Most of the youthful spectators, who had waited since before dawn to hear the American president, were too young to remember the cold war or the Prague Spring of 1968.

He described a 21st century in which nuclear powers agreed to reduce arsenals, countries without nuclear weapons pledged not to acquire them and all countries enjoyed the right to civilian nuclear power, ideally drawing their fuel from a tightly controlled “international fuel bank”.

He drew rather louder applause when he echoed the soaring rhetoric of his presidential campaign, suggesting that his election to office is the achievement that most inspired his audience. He earned resounding cheers when he talked about the turns of history that had allowed “someone like me” to become America's president.

Mr Obama said that America would seek a legally binding treaty with Russia on reducing stockpiles of strategic arms by the end of the year. His administration would also “immediately and aggressively” seek American ratification of the Comprehensive Test-Ban Treaty.

As a first step towards outlawing nuclear weapons, America should seek a new treaty that verifiably ended the production of fissile materials “intended for use in state nuclear weapons”. Existing non-proliferation agreements should be buttressed with beefed up inspections and “real and immediate consequences” for countries caught breaking the rules.

The president told the crowd that al-Qaeda wanted to obtain a nuclear bomb and described the prospect of nuclear-armed terrorists as the “most immediate and extreme threat to global security”. This hawkish talk did not impress his audience, who reacted with silence.

Working with Russia, Mr Obama went on, America would launch a new international effort to secure all vulnerable nuclear material around the world and work to thwart those smuggling such materials. America would host a summit on nuclear security within the next 12 months. But as long as nuclear weapons existed, America would maintain an arsenal powerful enough to deter any adversary and guarantee that defence to allies.

Other details were left distinctly vague. Mr Obama did not spell out what the “consequences” for rule-breaking nations might include. Hours before Mr Obama spoke in Prague, North Korea, the secretive Stalinist state, launched a long-range rocket apparently capable of being used as a missile. Mr Obama told the crowd this “provocation” underscored the need for (unspecified) action at the United Nations Security Council.

Czechs in the crowd were divided in their reactions when the American leader reiterated his support for an anti-missile defence system designed to ward off the threat from Iranian ballistic missiles.

“As long as the threat from Iran persists, we will go forward with a missile-defence system that is cost-effective and proven,” Mr Obama said, using wording that seemed to allow him wriggle room should missile-defence technology not prove its worth. If the Iranian threat were eliminated, the driving force for missile defence-construction in Europe would be “removed”, Mr Obama added.

He continued his day in Prague by meeting the 27 leaders of the European Union's member nations for a brief summit hosted by the Czech government, which holds the rotating six-month presidency of the EU, a task somewhat complicated by the collapse of that same government in a failed confidence vote late last month. Tensions showed. A plea from Mr Obama to “anchor” Turkey in Europe by pressing ahead with talks on admitting Turkey to the EU earned a public rebuke from Nicolas Sarkozy, who said that was a matter for members of the EU. In line with his country's public opinion, he believes Turkey should never be given full membership of the European club.