COLLEVILLE-SUR-MER, France (AP) -- Men who stormed Normandy's shore 70 years ago joined world leaders today in paying tribute to the 150,000 Allied troops who risked and lost their lives in the D-Day landings in Nazi-occupied France, in a day of international commemorations of history's biggest amphibious invasion.
They are honoring the troops and civilians who fell in mighty battles that helped bring Europe peace and unity -- just as bloodshed in Ukraine is posing new challenges to European security and threatening a new East-West divide.
As the sun rose today over a gusty Omaha Beach, flags flew at half-staff. A U.S. military band played Taps, while D-Day veterans from the 29th Infantry Division and serving soldiers stood at attention at exactly 6:30 a.m., the moment on June 6, 1944, when Allied troops first waded ashore.
"Twenty-nine, let's go!" they shouted, then downed shots of Calvados, Normandy apple brandy.
Hundreds of Normandy residents and other onlookers applauded the veterans, then began forming a human chain on the beach.
World leaders and dignitaries including President Barack Obama and Queen Elizabeth II are converging on Normandy to honor the more than 150,000 American, British, Canadian and other Allied D-Day troops who risked and gave their lives to defeat Adolf Hitler's Third Reich.
The D-Day invasion was a turning point in World War II, cracking Hitler's western front as the Soviet troops made advances in the east. Overall at least 4,400 Allied troops were killed the first day, and many thousands more in the ensuing three-month Battle of Normandy, which brought the Allies to Paris to liberate the French capital from Nazi occupation.
Russian President Vladimir Putin is also in attendance, invited by French President Francois Hollande in a gesture toward the 27 million Soviet citizens killed in World War II.
The D-Day commemorations are also offering a moment to try to reconcile Russia and Ukraine, and Russia and the West.
Putin was to meet with German Chancellor Angela Merkel in Deauville on the Normandy coast this morning, after meeting Hollande and British Prime Minister David Cameron on Thursday night. Ukraine's president-elect is also coming to Normandy.
The encounters marked the first time the isolated Russian leader has met Western leaders since pro-European protests in Kiev pushed out Ukraine's Russian-leaning president in February and Russia annexed the Crimean Peninsula.
Back in Normandy, several thousand veterans, family members and others gathered at the Normandy American Cemetery and Memorial, with its 9,387 white marble tombstones on a bluff overlooking the site of the battle's bloodiest fighting at Omaha Beach, the emotional centerpiece of pilgrimages to honor the men killed in Normandy.
Soldiers of 173rd Airborne brigade, the ceremony organizers, served as ushers, wearing maroon berets.
Obama declared June 6 a national remembrance day.
Ceremonies large and small are taking place across Normandy, ahead of an international summit today in Ouistreham, a small port that was the site of a strategic battle on D-Day.
Jeffrey McIllwain, professor at the San Diego State University school of public affairs, will lay a wreath on behalf of educators who have lost students to wars in Iraq and Afghanistan -- himself included.
He, like many veterans and world leaders here, is concerned about keeping the memory of D-Day alive as the number of survivors dwindles.
He brought 12 students to Normandy for a course on the lessons of D-Day.
"I make them promise to bring their grandchildren to serve as a bridge to the next generation," he said.