He served with the Virginia Army National Guard as an infantryman with Alpha Company, 1st Battalion, 183rd Infantry Regiment.

In September 1995, Hasson transferred to the Arizona Army National Guard and left in March 1996, exiting with the same rank as when he joined.

[3] In court filings, prosecutors wrote that Hasson drew inspiration from Norwegian terrorist Anders Behring Breivik and abortion clinic bomber Eric Robert Rudolph.

Hasson was planning to use biological weapons such as the Spanish flu, botulism, and anthrax to "kill almost every last person on the earth", followed by attacks on the food supply.

He recommended building stockpiles in five locations, the contents of which were to be food, firearms, clothing/military gear, and extra mortar recoilless rifles.

Hasson wanted to use tactics from the Euromaidan protests and the Donbass conflict in Ukraine in order to raise tensions between the "govt/police" and "BLM protestors and other leftist crap".

[21] Federal investigators executed search warrants at Hasson's apartment and office in Silver Spring, Maryland.

[8][23] Seven rifles, two shotguns, four pistols, two revolvers, and two silencers, along with magazines and ammunition and the opioid tramadol, were found in his home.

[3] Federal prosecutors wrote that Hasson intended "to murder innocent civilians on a scale rarely seen in this country" and described him as "a domestic terrorist, bent on committing acts dangerous to human life.

However, prosecutors appealed this decision and it was immediately reversed by US District Court Judge George J. Hazel, who ordered that Hasson continue to be detained pending trial, citing the potential dangers to the community.

(Under US federal law, a person who is a "unlawful user and addict of a controlled substance" is prohibited from owning firearms).

"[34] Vegas Tenold, author of the book Everything You Love Will Burn: Inside the Rebirth of White Nationalism wrote an op-ed on The Guardian titled "The neo-Nazi plot against America is much bigger than we realize" about Hasson and other far-right domestic terrorists.