Michael Masecchia, a teacher at a New York high school, is accused of drug trafficking going back 20 years.
Houthi rebels in Yemen, backed by Iran, have claimed responsibility for the attack.
Sources told Newsweek that the U.S. Army attempted to keep the incident quiet since the soldiers' arrest last November.
Various Fox News hosts blamed Democrats for creating a dangerous political environment.
The men were plotting an operation with hand grenades, automatic weapons, explosive belts and a car bomb.
An ATF official said the agency did not believe the suspected theft was terrorism-related.
Unexploded bombs from World War II are a persistent hazard in Germany, even more than 70 years since the end of the war.
The military-grade flares can be purchased at civilian sites like Amazon.
The State Department said Australia had requested up to 2,950 small-diameter bombs and up to 50 guided test vehicles.
It's unclear whether the arrests were linked to a heightened security alert Geneva authorities declared on Thursday.
Munitions pollute a vast area of land in the U.S., larger than the state of Maine.
Homeland Security Secretary Jeh Johnson has ordered the acting administrator's reassignment.
An internal Homeland Security investigation shows widespread failures by TSA agents.
Two men suspected of buying explosives to make pipe bombs to detonate during protests were arrested Friday.