The president doesn’t read history. So one must hope that his more learned associates will tell him the story of the USS Pueblo. His defense secretary Jim Mattis and national security advisor H.R. McMaster could do it.

The Pueblo is a permanent exhibit at the Pyongyang Victorious War Museum, the only commissioned U.S. Navy vessel being held captive. It’s a symbol of the folly of issuing military threats and of President Lyndon B. Johnson’s lost credibility.

North Korean forces captured the U.S. spy ship inside their territorial waters (or outside, depending on whom you believe) in late January, 1968. Donald Trump at the time was using medical deferments to avoid the draft. Now, as U.S. president, he has issued a threat and ordered a carrier strike force to head toward Korean waters.

On April 11 he tweeted, “North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them! U.S.A.” Then he told an interviewer, “We are sending an armada—very powerful” to North Korea. And after some initial confusion regarding its whereabouts, the USS Carl Vinson and its support vessels reversed course and headed toward North Korea, picking up two Japanese destroyers along the way.

What happens when they arrive in a few days remains to be seen, but here is what happened to the Pueblo and its 83 crew members.

For several days they were buzzed and harassed by North Korean vessels and aircraft while they sailed near North Korea, presumably gathering intelligence. Attempts were made to board the Pueblo, but when the captain successfully maneuvered the ship to thwart the boarding the North Koreans fired at it, killing one crew member.

As machine gun fire continued, the Pueblo signaled that it would allow boarding and its crew began destroying classified documents. Only a small percentage was successfully destroyed, and though the ship remained in radio contact with higher headquarters neither the Navy nor the Air Force was able to reach the Pueblo before the capture was complete and the Pueblo was towed to Wonsan harbor.

President Johnson responded with a massive show of military force eventually involving six aircraft carriers and associated vessels, some 200 aircraft, and a partial mobilization of reservists, the first since the Cuban missile crisis. Soon Johnson’s move was matched by the arrival of a number of Soviet ships in support of North Korea.

The American plan was to send a small destroyer into the harbor to tow the Pueblo out, but the harbor was heavily guarded and eventually Johnson opted to undertake a diplomatic approach, ordering the ships into South Korean waters.

The negotiation was conducted at Panmunjom and proved an enormously frustrating undertaking that followed exactly the scenario predicted by two American diplomats in a cable from Seoul to the State Department.

The U.S. side, they said, would be handed a document confessing to and apologizing for every act of which the North Koreans accused them. No changes to the document would be accepted over the entire negotiation. If the United States wanted its crew back, plus the body of the dead sailor, it would sign. The ship would not be returned.

Meanwhile the commander of the Pueblo, Capt. Lloyd Bucher, was subjected to psychological torture including a fake firing squad and the threat of executing his crew one by one in his presence.

After 11 months of fruitless negotiation the American side signed the document, the crew and body of the dead sailor were returned, the ship became a North Korean trophy, and the credibility of President Johnson’s military threat was destroyed. A possible shooting war, involving not just North Korea but the Soviet Union and China, was avoided at the cost of U.S. prestige.

Today we have a North Korean dictator of unknown stability and an American president with a fragile ego, a distaste for standing down in a crisis, and a deeply damaged diplomatic corps.

The crisis Trump is facing is clearly one that requires careful diplomacy instead of blustery military threats. He will be tested perhaps, and we will find out whether he has the courage to use diplomacy when diplomacy is needed.