What key characteristic differentiates 'likelihood' from 'vulnerability' in a homeland security threat assessment?

Likelihood refers to the probability or chance that a threat will actually occur, whereas vulnerability refers to the weaknesses or gaps in security measures that make an asset susceptible to harm if a threat materializes. Likelihood assesses how likely an adversary is to attempt an attack, based on factors like their intent, capability, and past behavior. Vulnerability, conversely, examines the inherent flaws or inadequacies in a system, facility, or process that could be exploited if an attack occurs. For example, a critical infrastructure facility might have a high vulnerability due to outdated security technology, but the likelihood of an attack could be low if there are no known active threats targeting that specific facility. In essence, likelihood focuses on the threat actor's behavior, while vulnerability focuses on the target's weaknesses.