Details of the plot
The Project 571 Outline was not written in the form of a practicable military plan, but more as political declaration. Of the nine sections of the Outline, only two deal directly with military strategy; the remaining sections either criticize the politics of the Cultural Revolution or attack the personality of China's leader, Mao Zedong. Because the writers of the Outline apparently lacked both the military knowledge and the ability to mobilize large groups of forces, Western scholars generally reject the possibility that Lin Biao could have personally planned Project 571.
Of the sections which deal with military strategy, the Outline's authors mention the support of a number of disparate forces, none of which was overwhelmingly powerful. The plotters believed they were supported by the equivalent of approximately six to eight Air Force divisions: the Fourth and Fifth Air Force Corps; the Ninth, Eighteenth, and Thirty-Fourth Air Force Divisions; the Thirty-Fourth Tank Regiment; and (perhaps unusually) the Bureau of Civilian Aviation. The authors also noted that they expected the support of an "auxiliary force" composed of the Twentieth and Thirty-Eighth Armies (Lin Biao's own elite units) and several provinces, which were only vaguely mentioned. The power of this combination of forces was not great, compared to the rest of the People's Liberation Army, and the authors of the Outline noted that "at present the preparation of our strength is still not adequate".
The military plans contained in the Outline were below the standards that could have been expected from Lin Biao, one of modern China's most successful generals. Because Lin Biao was a master of maneuvering ground forces, it is unusual that he would have relied almost exclusively on the Air Force, even though his own elite forces were readily available to him. In the Chinese Civil War, Lin had become a master of delaying decisive confrontations until he knew that the chances of victory had become overwhelming, and scholars note that it would have been out of character for Lin to have staked his political career on such a poorly planned military coup, whose chances of success were slim. There is no direct evidence that suggests that either Lin or his generals were involved in the coup plot. Many scholars believe that his son, Lin Liguo, a high-ranking officer in the People's Liberation Air Force, was instead the author. Within China, the theory that Lin Liguo drafted the Project 571 Outline was corroborated by the testimony of Lin Biao's generals in the special trials of the "Lin Biao and Jiang Qing Counter-Revolutionary Cliques", which were held in 1980.