Private Superforecasting Workshop asks:
Will there be a complex coordinated terrorist attack (CCTA) in the United States either directed or inspired by a foreign terrorist organization before 1 September 2021?
CCTAs are a major concern for law enforcement and emergency planners (FEMA). For the purposes of this question, a CCTA is an  act of terrorism  involving multiple perpetrators working in concert  initiated with little or no warning  and employing one or more weapon systems (e.g., firearms, explosives, fire as a weapon, poison gas)  that is intended to result in large numbers of casualties. For the purposes of this question, "terrorism" is as defined by federal law in 18 U.S.C. § 2331(5) (Cornell). A foreign terrorist organization (FTO) is an organization designated as an FTO by the US Department of State (State.gov). Examples of CCTAs include the 2004 Madrid train bombings, the 2008 Mumbai attacks, 2013 Boston Marathon bombings, and the 2015 San Bernardino, CA, office attack.