The flight commander was nervous. Four months earlier, North Korea had captured the USS Pueblo spy ship, holding more than 80 crewmen hostage at a prison camp. Preflight intelligence reports indicated the North Koreans were still agitated about the snooping.
The plane had been flying over the Sea of Japan for about five hours when two North Korean MiGs pounced, firing a missile that killed all 31 crew members.
Nearly 50 years later, the incident has been mostly forgotten. But now, with North Korea girding for war - conducting frequent missile tests, threatening to shoot down U.S. planes, trading insults with President Donald Trump - historians and national security analysts are reexamining the 1969 attack, particularly declassified documents that reveal President Richard M. Nixon's struggle to retaliate amid the Vietnam War.
Short of all-out destruction of North Korea, Nixon's national security team couldn't promise that even targeted airstrikes wouldn't escalate the conflict, leading to untold deaths in South Korea and a wider conflict in the region, perhaps drawing in China and Russia.
"I think it's a problem that's still present today," said Robert A. Wampler, a senior fellow at the National Security Archive, a George Washington University think tank that successfully pushed for release of documents related to the incident. "What can you do to ensure that nothing else will happen?"
From Truman to Trump, North Korea has vexed 13 presidents - during the bloody Korean War, which claimed the lives of more than 33,000 U.S. military service members; in 1976, when North Korea attacked and killed several American soldiers with axes in the demilitarized zone; in 1994, when a U.S. military helicopter was shot down, leaving the co-pilot dead; in 2009, when North Korea sank a South Korean warship, killing 46 crew members.
Only now, there's a new wrinkle: nuclear missiles.
Just last week, the Pentagon warned lawmakers that a ground invasion would be required to secure all of North Korea's nuclear weapons sites and that U.S. forces could face biological and chemical weapons.
A pre-emptive U.S. military strike on North Korea would trigger "a large-scale peninsular and regional conflict, involving hundreds of thousands of troops and potentially hundreds of thousands of civilian casualties," a recent Brookings Institution report concluded.
Both sides are amping up the rhetoric.
Trump, visiting South Korea on Tuesday as part of a 12-day trip to Asia, said, "This is a problem that should have been taken care of a long time ago." In recent months, he has taken to calling North Korean leader Kim Jong Un "Little Rocket Man." Kim, in return, has called Trump a "mentally deranged U.S. dotard."
Beyond the name calling, the leaders have each threatened horrific destruction upon the other, with Trump promising "fire and fury."
To the families who lost relatives that day in 1969, the verbal missiles have been a traumatic flashback to the very real rocket North Korea fired at the Navy plane. Many belong to a Facebook group, sharing old photos and memories - and, lately, their views on the conflict.
"Someone just needs to be silent (president)," one member wrote, "and surprise the crap out of them like they did" to the downed spy plane.
Joe Ribar, a Texas police officer, was just three months old when his father, Lt. Joseph R. Ribar, was killed. His body and another were the only ones recovered in the rough waters of the Sea of Japan.
Ribar has a hunch about where the tensions are headed.
"I'm fully expecting," he said, "another plane to be shot down out there."
The plane North Korea shot down was an EC-121 - hulking and armed only with high-tech surveillance gear that monitored sensitive communications in the region, including in Vietnam.
Lt. Cdr. James H. Overstreet led the operation, code named "Deep Sea 129." He'd been on dangerous missions before, including harrowing flights in Vietnam. But something about this flight, over less dangerous international waters, made the 34-year-old pilot from Mississippi anxious.
"He told my mother he might not be coming back," said his son, Joe Overstreet, who was six years old at the time. "There was something different about this mission. He knew it."
Documents declassified in 2010 explain why.
Before the attack, military commanders "were aware of anomalous North Korean behavior," according to a 2015 unclassified article in a CIA intelligence journal. National security officials knew North Korea was becoming increasingly agitated by U.S. intelligence gathering missions, but there were disagreements about the seriousness of the threats.
Overstreet briefed crew members before the flight.
"He discussed a message from the commander of US Forces Korea, warning of unusually vehement and vicious language used by the North," the CIA paper said.
What the commander didn't know: In the days leading up to the attack, North Korea had been quietly moving fighter jets to a base just off the coast. U.S. intelligence identified the activity as preparation for pilot training. They were wrong.
The EC-121 took off unaccompanied by any protection. An Air Force tracking station monitored the flight on radar.
An urgent warning was sent. But the North Koreans fired, and the American plane was destroyed.
Henry Kissinger's phone rang at 1 a.m. It was the duty officer at the Pentagon notifying him of the attack.
Kissinger was then a special assistant to Nixon on national security affairs. He raced to his basement office in the West Wing to gather facts before phoning the president around 7 a.m., according to his memoirs.
It was the first national security crisis Nixon faced in office beyond the ongoing conflict in Vietnam.
Nixon certainly knew North Korea was a growing threat. The Pueblo incident occurred during the campaign. He assailed President Lyndon B. Johnson for not forcefully responding to what many saw as an act of war. Now Nixon faced the same dilemma.
"We were being tested," the president wrote in his memoirs. "And therefore force must be met with force."
But what type of force?
Johnson had considered a variety of military responses, including naval blockades and even nuclear strikes, according to declassified documents. He eventually decided it was too dangerous to respond.
In Nixon's case, declassified documents, administration memoirs, and other scholarly research reveal an extraordinary effort throughout the government to identify a military response not just to the attack on the U.S. plane, but to any future provocations by North Korea.
The options ranged from a single targeted airstrike on North Korean airfields to a limited nuclear attack - code named FREEDOM DROP - to a full-scale nuclear war.
But it quickly became clear that even the most limited responses risked wider conflict in the region, as well as depleting U.S. military power in Vietnam.
A memo to Nixon in the hours after the attack warned of "vigorous defense measures" from North Korea targeting the U.S. military and South Korean airfields. Even as Kissinger pushed for retaliation -- in his memoir, he called the administration's response "weak" - Nixon and Pentagon officials pushed back.
"It was a calculated risk that the North Koreans would not escalate the situation further if we retaliated with a single strike against one of their airfields," Nixon wrote. "But what if they did and we suddenly found ourselves at war in Korea?"
That had been a disaster the first time around. More than 5 million died in the Korean War.
In the end, Nixon ordered a show of naval force in the region and the resumption of reconnaissance flights - with protection.
Many people couldn't fathom why Nixon didn't respond with force, Overstreet, the son of the EC-121 commander, recalls his mother telling him. He later became a Navy pilot and learned the military reasons why Nixon sat on his hands.
"It probably hasn't changed that much over the years," he said.
But Overstreet also wonders whether the lack of a forceful U.S. response for decades just keeps emboldening North Korea.
"Now they've gone nuclear," he said. "I guess at the highest level, I prefer a strong stance toward North Korea over letting them do what they want."
Nixon swore North Korea would be dealt with eventually.
"They got away with it this time," he told Kissinger, "but they'll never get away with it again."
Now, decades later, another president is talking tough. Trump responded to North Korea's threat to shoot down U.S. military planes by vowing, "I'll fix that mess."
"It's called the military option," Trump said.
Part of a continuing series about facets of the past that remain relevant.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)