Silent Vector - A Critical Energy Infrastructure Simulation Exercise was a simulation of a credible terrorist threat to American critical infrastructure created by the Center for Strategic and International Studies(CSIS) that took place in October 2002. The simulation was modeled after the 2001 Dark Winter simulated bioterrorist attack, and produced by CSIS in collaboration with the ANSER Institute and the Oklahoma City National Memorial Institute for the Prevention of Terrorism.
According to CSIS, Silent Vector was designed to simulate possible U.S. reaction to a credible threat of terrorist attack (on U.S. critical energy infrastructure) when there is not sufficient information for effective protection. . . The overall purpose of the exercise was to assist the Administration and Congress in their attempts to improve the effectiveness of response during the pre-attack phase of a major terrorist incident."
The exercise employed a simulated National Security Council of senior policymakers with former senator Sam Nunn (who later became chairman of CSIS’s Board of Trustees) serving as scenario president.
The results of the exercise are summarized in this CSIS document.
Threat-Vulnerability Integration Methodology
After 9/11, CSIS developed what it calls Threat-Vulnerability Integration Methodology, "which is designed to answer the question of where are you most vulnerable to what kinds of attack." The methodology is designed to be a "tool to assess the terrorist threat and the vulnerabilities of potential targets, and use this knowledge to prioritize investments in security in accordance with risk."
The methodology was applied and refined in the Silent Vector exercise. According to CSIS, "Silent Victor demonstrated the need for an integrated approach to risk assessment." 
It is unclear whether the Silent Vector exercise compelled the U.S. government to contract with CSIS to implement Threat-Vulnerability Integration Methodology.
- Simulations and Tabletop Exercises page, Center for Strategic and International Studies website, accessed September 14, 2010.
- Embassy Security May Not Be Proportionate to New Terrorist Risk, Alan B. Nichols, Washington Diplomat, December 2002, accessed September 14, 2010.
- Threat Vulnerability Integration Methodology, CSIS website, accessed September 14, 2010.