In December 1945 the United States Army published a secret report analysing and assessing the security apparatus surrounding the Manhattan Project. The report states that the Manhattan Project was "more drastically guarded than any other highly secret war development." The security infrastructure surrounding the Manhattan Project was so vast and thorough that in the early days of the project in 1943, security investigators vetted 400,000 potential employees and 600 companies that would be involved in all aspects of the project for potential security risks.