The nearly 40-page document, dubbed the "Jericho Wall" by Israeli authorities, set point by point detail the type of attack launched by Hamas, which killed about 1200,<> people.
The document, highlighted by the New York Times, did not specify a date for the attack, but described it as "a systematic attack aimed at overrunning fortifications surrounding the Gaza Strip, capturing Israeli cities and storming key military bases, including the headquarters of a military division."
Hamas "followed the plan with astonishing precision," according to the document, which called for "a barrage of rockets fired at the beginning of the attack, drones to destroy security cameras and machine guns along the border, and the influx of militants into Israel en masse in gliders, motorcycles and on foot," all of which actually happened in the October 7 attack.
The plan also included details about the location and size of Israeli military forces, call centers and other sensitive information, raising questions about how Hamas gathered its intelligence and whether there were leaks within Israel's security establishment.
The document was widely circulated among Israeli military and intelligence leaders, but experts determined that an attack of this magnitude and ambition "exceeds Hamas's capabilities," according to documents and officials.
It is unclear whether Prime Minister Benjamin Netanyahu or other senior political leaders have seen the document as well.
Officials with Israel's Gaza Military Division, which is responsible for defending the border with Gaza, said Hamas's intentions were unclear shortly after the document was obtained last year.
A military assessment seen by the newspaper said: "It is not yet possible to determine whether the plan has been fully accepted and how it will be implemented."
Then, in July, just three months before the attacks, a veteran analyst at Unit 3, Israel's signals intelligence agency, warned that Hamas had conducted an intensive day-long training that looked similar to what was in the plan, but a colonel in the Gaza Division ignored his concerns, according to encrypted emails seen by The New York Times.
"I completely refute that the scenario is fictional," the analyst wrote in the emails, said Hamas's drills perfectly matched "the content of the Jericho Wall," adding: "It's a plan aimed at starting the war. It's not just a raid on a village."
Israeli officials privately admit that "had the military taken these warnings seriously and redirected significant reinforcements to the south where it attacked Hamas, Israel could have mitigated or perhaps even prevented the attacks, but the IDF was not prepared to counter the influx of fighters from the Gaza Strip."
Israeli security officials have already acknowledged that they have failed to protect the country, and the government is expected to form a committee to investigate the events leading up to the attacks.
The Jericho Wall document reveals a series of mistakes that have lasted for years, culminating in what officials now consider Israel's biggest intelligence failure since the surprise attack that led to the 1973 war.
The basis behind all these failures was one largely inaccurate belief that Hamas lacked the ability to attack and would not dare to do so, a belief that officials said was so ingrained in the Israeli government that they ignored mounting evidence to the contrary.
The Israeli military and security service, which is responsible for fighting terrorism in Gaza, declined to comment on the New York Times report.
Israeli officials did not say how they obtained the Jericho Wall document, but it was among several copies of attack plans collected over the years, and a 2016 Defense Ministry memo, seen by The New York Times, says that "Hamas intends to take the next confrontation into Israeli territory."