If an incident is suspected to be a terrorist event involving a WMD, which agency takes the lead?

In the case of an incident suspected to involve a terrorist event with a weapon of mass destruction (WMD), the FBI is designated to lead the response. This is due to the Bureau's primary responsibility for handling domestic terrorism and incidents involving federal law enforcement. The FBI has specialized skills and resources, including the ability to conduct investigations and gather intelligence related to threats against public safety.

The nature of WMD incidents often requires coordination among various agencies; however, the FBI's role as the primary federal agency allows it to take the lead in managing the situation, ensuring the protection of the public, and orchestrating a response that involves local, state, and federal partners. This agency's jurisdiction over domestic terrorism supports its position as the go-to for such critical situations, where rapid assessment and coordinated action are necessary to mitigate threats and protect citizens.