- President Barack Obama pays tribute to U.S. servicemen at American Cemetery
- French President Francois Hollande honors civilian victims of World War II
- World leaders are to take part in a ceremony on Sword Beach, Normandy
- Russia's Vladimir Putin is attending the D-Day events amid tensions over Ukraine
(CNN) -- U.S. President Barack Obama paid tribute Friday to the U.S. servicemen 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, are part of a series of solemn events to commemorate the D-Day landings.
Obama pays tribute to D-Day veterans 
D-Day: By the numbers Obama, who arrived flanked by French President Francois Hollande, shook hands with some elderly veterans before the presentation of colors and playing of the two countries' national anthems.
Obama 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 Omaha 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?"
In his words, Hollande recalled how the calm beach below had become an "awful battlefield" on this day 70 years ago, the sea turning red with blood, and paid tribute to the courage of all those there.
He also thanked the United States and other Allied forces for their efforts to liberate Nazi-occupied France.
The moving ceremony concluded with a 21-gun salute and the playing of "Taps," as well as an overflight by military jets.
Obama and Hollande then 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.
Sword Beach
An international ceremony will be held later on Sword Beach in Ouistreham, Normandy.
UK Prime Minister David Cameron, German Chancellor Angela Merkel and Russian President Vladimir Putin are among those taking part in the D-Day events -- as are hundreds of World War II veterans.
Britain's Queen Elizabeth II is also present -- 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.
The D-Day landings, in which mainly British, U.S. and Canadian troops invaded occupied France, were a turning point in World War II.
More than 156,000 troops crossed the English Channel during the D-Day invasion in on June 6, 1944. Nearly 10,000 Allied troops were killed or wounded.
Nicholas Soames, grandson of Britain's wartime leader Winston Churchill, told CNN it was "very touching" that so many people had come to take part in what will likely be the last commemoration of the D-Day landings on this scale, since those who survived are now in their 80s and 90s.
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German soldier reflects on Normandy 
D-Day: Russia's sacrifice 
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. 
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. 
His close relationship with many of the people he photographed means his pictures are particularly intimate and candid. 
He took more than 8,000 photographs, following the progress of his unit from the beaches of Normandy to Berlin. 
The images show the fighting ... 
... and the devastation it left behind. 
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. 
After the war, Vaccaro became a professional portrait photographer, taking pictures of stars including Charlie Chaplin, Marlene Dietrich and Pablo Picasso. Tony Vaccaro: The soldier armed with a camera Civilian cost
Earlier, Hollande spoke at a war memorial in the city of Caen, Normandy, 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.
While 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 Bayeux War Cemetery, the largest of the Commonwealth cemeteries in France.
A fireworks display was staged Thursday night along the Normandy coastline where the landings took place.
Diplomatic maneuvers
The run-up to the commemorations has been dominated by the current crisis in Ukraine, which has sparked the worst East-West tensions since the end of the Cold War.
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.
While both Putin and Obama are attending the D-Day events, they have no scheduled meeting -- although the U.S. President has said it's likely their paths will cross.
Hollande dined separately with each of the two leaders Thursday evening.
The D-Day events may also bring Putin and Ukraine's President-elect Petro Poroshenko face to face.
Asked in an interview with French television station TF1 if he would speak with Ukraine's new leader, Putin said he will not "evade" Poroshenko or anyone else.
Poroshenko also did not exclude the possibility of a meeting.
At a news conference Thursday, Obama said the G7 nations were united in their support of Ukraine and urged Putin to take steps to deescalate the pro-Russia separatist unrest in the country's East.
Putin "has a chance to get back into a lane of international law," Obama said. But for this to happen, he said, Putin must take steps over the coming weeks that include engaging with Ukraine's new President, stopping the flow of weapons over the border into Ukraine and ceasing Russian support for pro-Russia separatists in Ukraine.
Poroshenko, who was elected last month, is due to be sworn in on Saturday.
READ: Obama vows to stand with Ukraine as he meets President-elect in Poland
READ: Opinion: Putin's empire building is not a new Cold War
READ: Russia and Ukraine bicker in U.N. meeting
Astronomers using the Hubble Space Telescope have pieced together this picture that shows a small section of space in the southern-hemisphere constellation Fornax. Within this deep-space image are 10,000 galaxies, going back in time as far as a few hundred million years after the Big Bang. Click through to see other wonders of the universe. 
Planetary nebula Abell 33 appears ring-like in this image, taken using the European Southern Observatory's Very Large Telescope. The blue bubble was created when an aging star shed its outer layers and a star in the foreground happened to align with it to create a "diamond engagement ring" effect. 
This long-exposure image from the Hubble Telescope is the 
NASA's NuSTAR telescope array generated the first map of radioactivity in the remnants of an exploding star, or supernova. Blue in this image of Cassiopeia A represents radioactive material. 
A supernova was spotted on January 21 in Messier 82, one of the nearest big galaxies. This wide view image was taken on January 22. 
The M82 supernova, seen here, has been designated SN2014J because it is the 10th supernova detected in 2014. At 11.4 million light years from Earth, it is the closest Type Ia supernova recorded since systematic studies with telescopes began in the 1930s. 
Is that a giant hand waving at us? Actually, it's what's left of a star that died and exploded a long time ago. Astronomers nicknamed it the "Hand of God." 
The Hubble Space Telescope captured this image of the Southern Pinwheel Galaxy, one of the largest and closest galaxies of its kind. 
Hubble scientists say this is the best-ever view of the Tarantula Nebula, which is located in one of our closest galactic neighbors, the Large Magellanic Cloud. 
Those spots on our sun appear small, but even a 
This Hubble image looks a floating marble or a maybe a giant, disembodied eye. But it's actually a nebula with a giant star at its center. Scientists think the star used to be 20 times more massive than our sun, but it's dying and is destined to go supernova. 
The "Follow Me To" photography project that made social media waves last year has been commissioned for a tourism campaign in Hong Kong. Here, Natalia Zakharova leads her photographer boyfriend Murad Osmann through the city's Global Geopark. 
They'll roll out a series of images over the course of the next few weeks. Here they're snapped by Hong Kong journalists as they ride on an open-top bus. 
The project comprises near-identical poses from the protagonists, but in different breathtaking spots around the world. This one's in Bali. 
The couple often take several different pictures in each city. This is one of their London portraits. 
The couple (here seen in New York) started the project after Zakharova got frustrated with Osmann's snap-happy antics during a trip to Barcelona in 2011. 
They've since traveled to dozens of cities to continue the photo series including Singapore (pictured) and most recently Hong Kong, where they've been commissioned by the Tourism Board. 
Their Hong Kong campaign is targeted at big-spending Russians, whose major travel season is winter. But this is not a full-time endeavor for the pair, who have to juggle the series around their day jobs. 
Future projects announced by Osmann include a series of videos that will show the work that goes into each photo, as well as some local attractions in each destination. 
Seattle Police SWAT officers run toward a campus building after a shooting on the Seattle Pacific University campus on Thursday, June 5, in Seattle. 
Brianna Clarke, a student at Seattle Pacific University, at the scene of the shooting. 
Students from Seattle Pacific University gather on campus in a prayer circle. 
Medical and police officers gather at the scene. 
Seattle Pacific University students are led out of the crime scene. 
Seattle firefighters load a victim into an ambulance near the scene of the shooting. 
Bystanders embrace near the scene of the shooting. 
Police officers conduct searches on students after a shooting occurred on the Seattle Pacific University campus. 
Emergency personnel gather near the scene of the shooting. 
Bystanders look on as emergency personnel arrive near the scene of the shooting. 
Law enforcement officers gather near the scene. 
