President Barack Obama led a solemn tribute on Saturday to the valiant Allied soldiers who stormed the beaches here 65 years ago and achieved the triumph of a generation that charted the course for the end of World War II. 'As we face down the hardships and struggles of our time and arrive at that hour for which we were born,' Obama said, 'we cannot help but draw strength from those moments in history when the best among us were somehow able to swallow their fears and secure a beachhead on an unforgiving shore.' With a new era of threats gathering, Obama and the leaders of France, Britain and Canada paused to reflect upon the heroics that took place during the D-Day operations on the beaches of Normandy and the cliffs of nearby Pointe du Hoc. The spirit of those battles, the presidents and prime ministers told the crowd, holds lessons for confronting the world's new challenges. The military ceremony came on the fourth day of Obama's trip across the Middle East and Europe, where the diplomatic goals of his administration came into sharper focus. As he made his way here, he signaled his intention to take a stronger tack toward North Korea, whose behavior he called 'extraordinarily provocative.' Obama delivered a 16-minute address steeped in history, following President Nicolas Sarkozy of France, Prime Minister Stephen Harper of Canada and Prime Minister Gordon Brown of Britain. The four men, along with Prince Charles of Britain, faced a crowd that stretched the length of the cemetery. 'The great totalitarian systems of the 20th century have been defeated,' Sarkozy said. 'The threats that loom over the future of humanity today are of a different kind, but they are no less serious.' Before arriving here for the afternoon ceremony, Obama met with Sarkozy in Caen, a city of churches nearly destroyed by Allied artillery and bombs. The two leaders said they found common ground on issues like the Middle East, Iran's nuclear ambitions and threats from North Korea, with Obama signaling a stronger approach toward that nation. 'We are not intending to continue a policy of rewarding provocation,' Obama said, referring to the latest nuclear test and missile test-launches by North Korea. 