A nuclear standoff. One leader is drunk. The other is delirious. The underlings scramble to avoid the worst. This is not an end-of-the-world Hollywood thriller, or an episode in President Trump’s erratic diplomacy. It is a story of how the United States and the Soviet Union found themselves on a collision course in the Middle East.

The Yom Kippur War, fought over several weeks in October 1973, was a tumultuous conflict between Israel and a coalition of Arab states, led by Egypt and Syria. The war ended with a decisive victory for Israel, but even 45 years later, questions about the roles played by the two Cold War superpowers remain.

Now, new documents, collected and translated by the Wilson Center, show the Kremlin in disarray, desperately trying to help Egypt, one of its most important client states. For many years we thought the aggressive Soviet behavior during the war was a ploy to undercut American influence, or gain access to oil or warm-water ports. The new evidence suggests it was simply a case of bad crisis management.

On the morning of Oct. 6, 1973, taking advantage of Yom Kippur, Egypt and Syria began a coordinated assault on Israel in a bid to retake the territories lost in the Arab-Israeli War six years earlier. Bolstered by a Soviet airlift, the Egyptians and the Syrians made early gains before Israel reclaimed the initiative on the battlefield. Ignoring a United Nations Security Council call for a cease-fire, the Israelis pressed on.

Two weeks later in Washington, while the war continued, President Richard Nixon forced out his attorney general and deputy attorney general, then fired the special prosecutor Archibald Cox. This Saturday Night Massacre unleashed a political firestorm and Mr. Nixon, bending in the face of all the fury, sought solace in drink. ...