Operation Dark Winter was a simulation in 2001 about a bio attack on the United States

Operation Dark Winter was the code name for a senior-level bio-terrorist attack simulation conducted on June 22–23, 2001.It was designed to carry out a mock version of a covert and widespread smallpox attack on the United States. Tara O'Toole and Thomas Inglesby of the Johns Hopkins Center for Civilian Biodefense Strategies (CCBS) / Center for Strategic and International Studies (CSIS), and Randy Larsen and Mark DeMier of Analytic Services were the principal designers, authors, and controllers of the Dark Winter project.

The leaders of two controversial pandemic simulations that took place just months before the Coronavirus crisis – Event 201 and Crimson Contagion – share a common history, the 2001 biowarfare simulation Dark Winter. Dark Winter not only predicted the 2001 anthrax attacks, but some of its participants had clear foreknowledge of those attacks.
Source: https://www.thelastamericanvagabond.com/all-roads-lead-dark-winter/