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The thorny problem of relations with North Korea is decades old. That troubled relationship was highlighted in March with a North Korean torpedo attack on a South Korean naval ship. The ship sank and 46 sailors died.
But so far, neither South Korea nor the United States has figured out how to respond. Such was the case, too, in 1969 when North Korean fighter jets shot down an American spy plane.
Newly disclosed documents show that then President Nixon and his national security adviser, Henry Kissinger, considered a whole range of military responses up to the possible use of nuclear weapons. But they, too, decided to do nothing.
NPR's Mike Shuster reports.
MIKE SHUSTER: The incident occurred on April 15, 1969. An American EC-121 reconnaissance plane carrying a full crew took off from a base in Japan and did what it had done dozens of times before. It flew over international waters gathering signals, radio communications and other intelligence.
This time, though, fighter jets from North Korea intercepted the American plane and shot it down, killing all 31 Americans on board.
In the immediate hours after the attack and for the next few months, President Nixon and his advisors struggled to come up with a response, according to Robert Wampler, a historian who works for the National Security Archive, a project of George Washington University.
Dr. ROBERT A. WAMPLER (Research Fellow; National Security Archive, George Washington University): The U.S. did not have a very good menu of options when this happened, which sort of constrained them in their ability to pick and choose amongst something that would work and also contain the situation.
SHUSTER: Wampler recently posted 16 documents on the website of the National Security Archive, among some 1,700 that he has been studying. They illustrate vividly just how difficult it was for Nixon to respond to the North Korean attack in such a way that would not spark a wider war.
Two months after the attack, the documents show the option of using nuclear weapons was presented to the president.
Dr. WAMPLER: The military produced the options, ratcheting up the level of military force all the way to all-out war and to using nuclear weapons. But constantly, you find the military saying: But the risks probably still outweigh the potential gains.
SHUSTER: These documents do not address what Nixon and Kissinger considered doing in the immediate hours after the attack. By the time that the nuclear option arose, Nixon was considering what his choices might be in the next provocation from North Korea.
But a former U.S. fighter pilot has come forward with a story about a nuclear alert, just hours after the attack. Bruce Charles was on temporary duty that day at Kunsan Air Force Base in South Korea. He was on standard alert as part of the Single Integrated Operational Plan, or SIOP, the plan for nuclear war with the Soviet Union. His assigned target was an airstrip in North Korea.
Early that afternoon, his commanding officer called him into his office, Charles says.
Mr. BRUCE CHARLES (Former U.S. Fighter Pilot): When I got to see the colonel, it was very simple. He described the shooting down of the EC-121 about a hundred miles at sea, and that he had a message, which he showed me at that time, saying to prepare to strike my target.
SHUSTER: Charles then rechecked his F-4 fighter jet and the weapon it was carrying. He says it was a B61 nuclear bomb with a yield of about 330 kilotons - not the biggest bomb in the U.S. nuclear arsenal, but quite large - more than 20 times the size of the bomb dropped over Hiroshima.
Then there were several hours of waiting, Charles says, and the order came to stand down.
Mr. CHARLES: The order to stand down was just about dusk, and it was not a certainty. The colonel said: It looks like from the messages I'm getting, we will not do this today. I do not know about tomorrow.
SHUSTER: Charles' story could not be independently confirmed. But not long after the North Korean attack, The New York Times, citing sources in the Nixon administration, reported that there was discussion of a nuclear attack against North Korea.
Morton Halperin worked at that time in the National Security Council. He believes President Nixon did decide to retaliate against North Korea. But, says Halperin, he has no knowledge that a nuclear strike was considered.
Dr. MORTON HALPERIN (Senior Advisor, Open Society Institute): Nixon had made a decision that we would retaliate by bombing the air base from which we believed the planes had come to shoot down the EC-121. And he had ordered an aircraft carrier to move close enough to be able to carry out the bombing.
SHUSTER: Two days after the attack, though, Nixon held a press conference. And what he said led many in Congress to conclude he was not opting for retaliation. He was praised widely for this restraint, Halperin recalls, and then decided against a military response.
The documents posted by the National Security Archive suggest that for half a century, American presidents have had the same problem with North Korea, says Dan Sneider of the Asia-Pacific Research Center at Stanford.
Mr. DAN SNEIDER (Associate Research Director; Asia-Pacific Research Center, Stanford University): The danger of a wider war tends to trump whatever benefit you think might come from punishing your enemy here with a retaliatory strike.
SHUSTER: That's precisely the dilemma the Obama administration has been struggling with since March, when a North Korean submarine sank the South Korean ship Cheonan with a single torpedo.
Mike Shuster, NPR News.