ABC News reports that the FBI has arrested 20-year-old Christopher Lee Cornell of Green Township, Ohio for planning what ABC describes as “an ISIS-inspired attack on the U.S. Capitol, where he hoped to set off a series of bombs aimed at lawmakers, whom he allegedly considered enemies.”

The plan evidently involved seeding the Capitol with pipe bombs, and using guns to murder survivors of the explosions as they fled.

Cornell got on the FBI’s radar screen by praising jihad and expressing support for ISIS online:

The FBI first noticed Cornell several months ago after an informant notified the agency that Cornell was allegedly voicing support for violent “jihad” on Twitter accounts under the alias “Raheel Mahrus Ubaydah,” according to charging documents. In addition, Cornell allegedly posted statements, videos and other content expressing support for ISIS — the brutal terroristgroup also known as ISIL — that is wreaking havoc in Iraq and Syria.

“I believe that we should just wage jihad under our own orders and plan attacks and everything,” Cornell allegedly wrote in an online message to the informant in August, according to the FBI. “I believe we should meet up and make our own group in alliance with the Islamic State here and plan operations ourselves.”

In the message, Cornell said that such attacks “already got a thumbs up” from radical cleric Anwar Awlaki “before his martyrdom.”

The FBI was concerned enough to arrange meetings between Cornell and the informant, moving in after it became clear that Cornell had entered the “final steps” of preparing for his attack, including the purchase of two semi-automatic rifles and 600 rounds of ammunition from a store in Ohio.

ABC relates a statement from the Department of Homeland Security to law enforcement nationwide:

The alleged activities of Cornell highlight the continued interest of US-based violent extremists to support designated foreign terrorist organizations overseas, such as ISIL, by committing terrorist acts in the United States. Terrorist group members and supporters will almost certainly continue to use social media platforms to disseminate English language violent extremist messages.

According to Fox News, the charges filed against Cornell include “the attempted killing of a U.S. government officer and possession of a firearm in furtherance of attempted crime of violence.”  A Justice Department official is quoted describing Cornell as “aspirational and not operational,” meaning he was arrested before his plot came anywhere near fruition.