Seventh Review Conference in 2011): CBM A: (i) research centres and laboratories, and (ii) national biological defence research and development programs CBM B: outbreaks of infectious diseases and similar occurrences caused by toxins CBM C: efforts to promote research results CBM E: legislation, regulations, and other measures CBM F: past activities in offensive and/or defensive biological research and development programs CBM G: vaccine production facilities While the number of CBM submissions has increased over time, the overall participation rate remains low at less than 50 percent. In 2018, an online CBM platform was launched to facilitate the electronic submission of CBM reports. An increasing number of states are making their CBM reports publicly available on the platform, but many reports remain only accessible to other states. The history and implementation of the CBM system have been described by the BWC Implementation Support Unit in a 2016 report to the Eighth Review Conference. Failed negotiation of a verification protocol Unlike the chemical or nuclear weapons regimes, the BWC lacks both a system to verify states' compliance with the treaty and a separate international organization to support the convention's effective implementation. Agreement on such a system was not feasible at the time the BWC was negotiated, largely due to Cold War politics but also due to a belief it was not necessary and that the BWC would be difficult to verify. U.S. biological weapons expert Jonathan B. Tucker commented that "this lack of an enforcement mechanism has undermined the effectiveness of the BWC, as it is unable to prevent systematic violations". Earlier drafts of the BWC included limited provisions for addressing compliance issues, but these were removed during the negotiation process. Some countries attempted to reintroduce these provisions when the BWC text was submitted to the General Assembly in 1971 but were unsuccessful, as were attempts led by Sweden at the First Review Conference in 1980. Following the end of the Cold War, a long negotiation process to add a verification mechanism began in 1991, when the Third Review Conference established an expert group on verification, VEREX, with the mandate to identify and examine potential verification measures from a scientific and technical standpoint. During four meetings in 1992 and 1993, VEREX considered 21 verification measures, including inspections of facilities, monitoring relevant publications, and other on-site and off-site measures. Another stimulus came from the successful negotiation of the Chemical Weapons Convention, which opened