Amongst the tens of thousands of CIA documents put online, one can find the American intelligence assessment regarding the possibility of a war between Israel and its neighbors in 1973 and how the then-US Secretary of State Henry Kissinger acted when he received the information that Egypt and Syria were intending to begin the Yom Kippur War.
In the daily intelligence briefing submitted to the then-US President, Richard Nixon, on the day that the war broke out, it was reported, "Both the Israelis and the Arabs are becoming increasingly concerned about their adversaries' military activities, but neither side seems bent on starting hostilities."
A CIA document from October 6, the day the war broke out, reported that six Soviet military planes "flew to Damascus yesterday. In addition a Soviet jet transport normally used for VIPs made two round-trip flights to Cairo. The air-lift continues today.
"Most of these flights probably are being used to evacuate Soviet dependents from Egypt and Syria."
According to the Americans, then-Israeli Prime Minister Golda Meir's government was not too concerned with the possibility of an impending attack, writing the day before the war that Israel saw the Egyptians' maneuvers as normal and Syria's as defensive. It considered that Syrian concerns could lead to military deployment, causing an Israeli reply that would continue to grow and balloon into a war that nobody wanted.
However, the next day, the US received updated intel that completely changed their appraisal. They received "information from 'good sources' that Egypt and Syria are planning a coordinated attack across the Suez Canal and the Golan Heights before nightfall today."
Kissinger transmitted a message to Nixon via the White House situation room, warning, "At 6:00am this morning (1pm Israel time), I was notified that the Israelis have what they consider to be hard information that Egyptians and Syrians were planning to launch a coordinated attack within six hours." The Egyptians and the Syrians actually ended up attacking at 1:55pm.
Kissinger contacted the Soviet ambassador to the US, Anatoly Dobrynin "and told him of the Israel demarche. I emphasized to him that:
"—The US and the USSR have a special responsibility to restrain their respective friends,
"—We are urgently communicating with the Israelis, warning them against any preemptive attack." The secretary of state said that he told the ambassador that the most important was to avoid a military conflict.
Kissinger reported to the president that Dobrynin agreed to phone Moscow and ask them to restrain the Arab states. The Soviet was permitted to use US communications system to do so more quickly.
Kissinger then contacted the then-head of the IDF Chief of Staff''s office, Avner Shalev. Both of them along with Meir, agreed with the American position against a preemptive strike. The secretary of state contacted Egypt's foreign minister, Jordan's King Hussein, and Saudi Arabia's King Faisal, asking the royalty to intervene with Syria and Egypt's presidents to forestall war.