Survivors of the attack on Pearl Harbor joined in a moment's silence Wednesday, as flags were lowered across the US to mark the 70th anniversary of Japan's history-changing attack.
Defense Secretary Leon Panetta recalled how the surprise Japanese assault "awoke a sleeping giant" as the United States responded by joining its European allies in World War II.
Crowds gathered at Pearl Harbor, west of Honolulu, bowed their heads for a moment to mark 7:55 am (1755 GMT), the exact time when the devastating Japanese air bombardment began on the morning of December 7, 1941.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"Seventy years ago... our nation sustained a cruel and destructive attack. Our enemies thought that by this sudden and deliberate raid they could weaken America," said Panetta, in a letter read out to the memorial.
"Instead they only strengthened it. That day truly awoke a sleeping giant."
The crowd applauded as dozens of survivors of attack were asked to stand, some saluting, shortly after a flypast by three F22 jets in the blue skies over the Hawaii ceremony.
Ceremonies were held from the Pacific island state of Hawaii to Washington DC on the US East Coast to remember the 2,400 Americans who died when Japan launched a devastating surprise attack.
President Barack Obama called for the Stars and Stripes to be flown at half mast on federal buildings across the country, to mark National Pearl Harbor Remembrance Day.
"We salute the veterans and survivors of Pearl Harbor who inspire us still. Despite overwhelming odds, they fought back heroically, inspiring our nation and putting us on the path to victory," Obama said in a statement.
Some 2,400 people were killed in the two-hour Japanese attack on the US Pacific Fleet, anchored in Hawaii, while some 20 ships were sunk or damaged and 164 planes destroyed.
Denouncing "a date which will live in infamy," president Franklin Roosevelt declared war on Japan, leading the United States into World War II at a time when many of his countrymen had hoped to avoid the conflict.
For decades, some conspiracy theorists have believed that president Roosevelt had received intelligence about the Japanese attack before it happened, but willingly chose not to act on it.
The theory goes that Roosevelt believed the shock of the attack would persuade Americans of the need to enter the war.
It is based on the fact that US military radar failed to detect the approach of six Japanese aircraft carriers with 400 planes on board, which stopped 220 miles (350 km) from their target.
But the theory has been dismissed by some experts.
"It's a legend," says military historian Daniel Martinez, who works for the Pearl Harbor National Monument in Hawaii. "This is the kind of conspiracy theory fabricated for the profit of writing a book."
Whatever the truth, the day after Pearl Harbor, the US Congress officially declared war on Japan. Three days later, Germany declared war on the United States. The US entry into the war was to change the course of the conflict.
In his tribute Wednesday, Hawaiian-born Obama drew parallels to the current "9/11 generation" which went off to war in Afghanistan and Iraq following the September 11 attacks in 2001.
"We resolve to always take care of our troops, veterans and military families as well as they've taken care of us," Obama said.
Republicans vying for the chance to succeed Obama in the White House also issued statements observing the historic date.
Congresswoman Michele Bachmann in a tweet urged her supporters to "please remember the victims of the #PearlHarbor attacks. The 'date of infamy' that forever changed America happened 70 years ago today."
