Story highlights UK veteran slips out of nursing home to attend 'first-class show' in France

Obama tells Putin he risks further isolation if he doesn't work with Kiev

French President Francois Hollande hails heroes who died on Normandy beaches

Putin and Ukraine's president-elect also speak at the lunch for leaders

President Barack Obama paid tribute Friday to the U.S. service members who "defied every danger" to pour onto the beaches of Normandy 70 years ago in defense of liberty.

His remarks at the American Cemetery in Colleville-sur-Mer, which overlooks Omaha Beach where so many fell, were part of a series of solemn events to commemorate the D-Day landings in northern France.

Chief among them is an elaborate international ceremony on the stretch code-named Sword Beach, in Ouistreham, for which world leaders and veterans took places in stands set up on the sand.

As the ceremony got under way under brilliant sunshine, military bands marched on a map of the globe laid out across the golden strand in front of French President Francois Hollande.

Hollande spoke of the bravery of the young men who waded ashore under a deluge of German fire seven decades earlier, through waters turned red with blood, hailing them all as heroes.

"I want to express my gratitude to all the fighters who are no longer here," Hollande said, going on to list the American, British, Canadian, Polish, Belgian and other forces that took part. He paid tribute to the many Russians who died during World War II and to the German victims of the Nazi regime.

D-Day by the numbers

Photos: The Allied invasion of Normandy Photos: The Allied invasion of Normandy American troops storm the beaches of Normandy, France, on June 6, 1944. D-Day was the largest amphibious invasion in history. More than 160,000 Allied troops -- about half of them Americans -- invaded Western Europe, overwhelming German forces in an operation that proved to be a turning point in World War II. Hide Caption 1 of 15 Photos: The Allied invasion of Normandy U.S. troops wait to disembark a landing craft on D-Day. Hide Caption 2 of 15 Photos: The Allied invasion of Normandy American troops help their injured comrades after their landing craft was fired upon. Allied forces secured the beaches at a cost of about 10,000 casualties. Hide Caption 3 of 15 Photos: The Allied invasion of Normandy French commandos equipped with bicycles disembark from their landing craft after Allied forces stormed the Normandy beaches. Germans rained mortars and artillery down on Allied troops, killing many before they could even get out of their boats. Fighting was especially fierce at Omaha Beach, where Nazi fighters nearly wiped out the first wave of invading forces and left the survivors struggling for cover. Hide Caption 4 of 15 Photos: The Allied invasion of Normandy The British Army's 50th Infantry Division lands on beaches in Normandy. This photograph is part of an exhibit in London at the Imperial War Museum Hide Caption 5 of 15 Photos: The Allied invasion of Normandy An aerial view shows 32 intentionally sunk American merchant ships that served as a breakwater as well as anti-aircraft platforms. Hide Caption 6 of 15 Photos: The Allied invasion of Normandy Traffic builds up on the beach and on the road leading to Le Hamel, France, during the landing of the 50th Infantry Division. Hide Caption 7 of 15 Photos: The Allied invasion of Normandy U.S. troops and vehicles are ready to disembark. D-Day was one of history's most consequential and gut-wrenching battles. Hide Caption 8 of 15 Photos: The Allied invasion of Normandy A sign outside of Trinity Church in New York invites worshippers to pray for Allied victory in the D-Day invasion. Hide Caption 9 of 15 Photos: The Allied invasion of Normandy Commandos with the Royal Navy's 4th Special Service Brigade advance to Juno Beach at Saint-Aubin-sur-mer. Hide Caption 10 of 15 Photos: The Allied invasion of Normandy Lance Cpl. Walter Ray of the British Army shares a bottle of rum he found floating in the sea. Hide Caption 11 of 15 Photos: The Allied invasion of Normandy U.S. Gen. Dwight D. Eisenhower, left, supreme commander of the Allied forces, and British Field Marshal Bernard Montgomery, right, discuss plans at an undisclosed location in June 1944. The Allies went to elaborate lengths to maintain secrecy and mislead Adolf Hitler. They employed double agents and used decoy tanks and phony bases in England to hide actual troop movements. Hide Caption 12 of 15 Photos: The Allied invasion of Normandy Eisenhower gives the order of the day to paratroopers in England. "Full victory -- nothing else" was the command just before they boarded their planes to participate in the first wave. The invasion -- code-named Operation Overlord -- had been brewing for more than two years. Hide Caption 13 of 15 Photos: The Allied invasion of Normandy British troops pose for a photograph with a French woman in La Breche d'Hermanville. Hide Caption 14 of 15 Photos: The Allied invasion of Normandy U.S. troops huddle behind the protective front of their landing craft as it nears a beachhead. Smoke in the background is naval gunfire, giving cover to troops on land. Hide Caption 15 of 15

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The Allied forces' sacrifice allowed Europe to live in security today, Hollande said in a speech that also highlighted the challenges the world now faces.

It was followed by a dance performance depicting the occupation, liberation and post-war reconstruction of Europe.

The D-Day landings, in which mainly British, U.S. and Canadian troops invaded Nazi-occupied France, were a turning point in World War II.

Obama: 'Democracy's beachhead'

Obama, speaking earlier at the American Cemetery, said he was honored to be there "to pay tribute to the men and women of a generation who defied every danger: among them, our veterans of D-Day."

Lengthy applause rang out as the U.S. President said he was humbled by the presence of some of those veterans at the ceremony.

"Here, we don't just commemorate victory, as proud of that victory as we are; we don't just honor sacrifice, as grateful as the world is; we come to remember why America and our allies gave so much for the survival of liberty at this moment of maximum peril," Obama said.

Their story should remain "seared into the memory of a future world," he said, describing Normandy as "democracy's beachhead."

He said, "It was here, on these shores, that the tide was turned in that common struggle for freedom.

"What more powerful manifestation of America's commitment to human freedom than the sight of wave after wave of young men boarding those boats to liberate people they'd never met?"

After the poignant ceremony, Obama and Hollande moved among the veterans and military officials, shaking hands and thanking them for their service.

The cemetery, which sits on a cliff overlooking Omaha Beach and the English Channel, contains the graves of 9,387 U.S. servicemen, most of whom lost their lives in the D-Day landings.

Omaha was the deadliest of the landing sites because German forces were able to fire from fortified positions on the cliffs above as the first waves of soldiers reached the shore.

Putin and Obama meet

A lunch for world leaders and veterans hosted by Hollande before the Sword Beach ceremony was the scene of an impromptu meeting between Obama and Russian President Vladimir Putin.

The pair spoke on the margins of the lunch in what Deputy National Security Adviser Ben Rhodes said was an informal conversation, not a formal bilateral meeting. It lasted 10 to 15 minutes, he said.

Photos: Tony Vaccaro: The soldier armed with a camera Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – G.I. Tony Vaccaro carried a camera as well as a gun when he landed in Normandy in June 1944, as part of the Allied Invasion Force. Hide Caption 1 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – Vaccaro was a member of the 83rd Infantry Division. His commanding officer gave him permission to take photographs of the unit's experiences during the war. Hide Caption 2 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – His close relationship with many of the people he photographed means his pictures are particularly intimate and candid. Hide Caption 3 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – He took more than 8,000 photographs, following the progress of his unit from the beaches of Normandy to Berlin. Hide Caption 4 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – The images show the fighting ... Hide Caption 5 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – ... and the devastation it left behind. Hide Caption 6 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – An exhibition of Vaccaro's photos, "Shots of War," is on display at the Caen Memorial, a stone's throw from Omaha Beach, as part of the 70th anniversary of D-Day. Hide Caption 7 of 8 Photos: Tony Vaccaro: The soldier armed with a camera The soldier armed with a camera – After the war, Vaccaro became a professional portrait photographer, taking pictures of stars including Charlie Chaplin, Marlene Dietrich and Pablo Picasso. Hide Caption 8 of 8

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Obama and Putin have been at loggerheads in recent weeks over Russian actions in Ukraine, and the pair were not seated next to each other for lunch.

The run-up to the commemorations has been dominated by the crisis in Ukraine, which has sparked the worst East-West tensions since the end of the Cold War.

Putin and Ukrainian President-elect Petro Poroshenko also talked briefly before the leaders went in to lunch in Benouville, with German Chancellor Angela Merkel standing between the two as they spoke.

G7 leaders have urged Putin to engage with Poroshenko, who will be inaugurated Saturday, as Ukraine's legitimate leader and take steps to ease the pro-Russia separatist unrest roiling eastern Ukraine.

Putin was excluded from a meeting of G7 leaders held this week in Brussels, Belgium, as part of measures to sanction Moscow over its annexation in March of Ukraine's Crimea region.

'Touching' commemoration

More than 156,000 troops crossed the English Channel during the D-Day invasion on June 6, 1944. Nearly 10,000 Allied troops were killed or wounded.

Nicholas Soames, grandson of British wartime leader Winston Churchill, said it was "very touching" that so many people had come to take part in what will probably be the last commemoration of the D-Day landings on this scale, since those who survived are now in their 80s and 90s.

Nearly 1,000 veterans have traveled to France to take part in the events, according to the French government.

Veteran Bernard Jordan, 89, went missing from his nursing home in Hove, a town on the south coast of England, on Thursday, wearing his war medals underneath his jacket, according to CNN affiliate ITV.

He was bound for the French shores once more.

But the nursing home didn't know and called police, the station said.

Jordan was found in France a day later marking the 70th anniversary with his friends. Another veteran called the care home to say he met Jordan on a coach to France and both men were well in a Ouistreham hotel, according to ITV News.

The affiliate caught up with Jordan on his return leg, about to board a ferry home.

He called the commemorations "a first-class show." He attended them last year.

"That was the main reason I came over here," he told the affiliate. "Touch wood ... if I'm still about, I should try it the next few years as well."

When the affiliate asked whether he would be in trouble back home, he laughed: "I might be, but I hope not." He was then escorted away.

Britain's Queen Elizabeth II is the only living head of state who served in World War II, working as a mechanic and military truck driver in the Women's Auxiliary Territorial Service.

'Strength of heart'

Earlier, Hollande spoke at a war memorial in the city of Caen at a ceremony to honor civilian victims and paid tribute to all those killed in the conflict.

He recalled the "strength of heart and bravery" of those who helped to liberate France from Nazi Germany, as well as the many victims in Normandy -- more of them civilians than soldiers.

Although the war may be long over in Normandy, Hollande said, "the war is still here in this tumultuous, uncertain and sometimes threatening world -- and in all wars, it is civilians who pay a heavy price."

The Queen, Prince Philip and Prince Charles took part in a ceremony at the British War Cemetery in Bayeux, the largest of the Commonwealth cemeteries in France.

Further along the French coast in Arromanches, the Duke and Duchess of Cambridge, William and Kate, attended a tea party for veterans, and each royal spoke separately with the silver-haired and beret-attired honorees.

Canadian Prime Minister Stephen Harper was also in Normandy to honor the Canadian forces that stormed Juno Beach 70 years ago.

"It is a source of enormous national pride that Canadians played such a pivotal role in ensuring the success of the D-Day landings," he said in a statement.

"We are also deeply humbled by the enormous sacrifices made by our fellow citizens, who with grim determination, stood shoulder to shoulder with like-minded allies to fight evil."

A fireworks display was staged Thursday night along the Normandy coastline where the landings took place.