Washington — A Department of Energy electrical engineer has been arrested on charges of providing support to the Iranian-backed Houthi rebels, including by buying materials for homemade explosives and drones and traveling to Yemen, the Justice Department said Thursday.

Ashton Hamed Ellaboudy, 51, of Richland, Washington, was arrested Thursday and is due to make his first court appearance Friday. Court records don’t list an attorney available to speak on his behalf.

The FBI says Ellaboudy had a goal of helping the Houthis improve their communications capabilities and traveled last September to Yemen, where the Houthis and Saudi-backed government forces are now engaged in renewed violence that has killed hundreds and displaced tens of thousands. The conflict began in 2014 when the Iran-backed rebels took over the capital, Sanaa, forcing the country’s government to settle into exile in Saudi Arabia.

Ellaboudy used a passport issued to him when he was working at the U.S. Army Corps of Engineers to make his way to Oman, then bordering Yemen, the Justice Department said.

Upon his return to the United States, authorities say, Ellaboudy told Customs and Border Protection officials that he was traveling back from Oman on a work trip and was part of a U.S. government mission to inspect missile defense systems. But investigators interviewed Ellaboudy’s supervisor, who reported having no knowledge of any international travel or of an Energy Department missile inspection program that Ellaboudy would have been assigned to, an FBI affidavit said.

Ellaboudy himself was recorded telling FBI informants, whom officials had introduced into the investigation, that he had to be smuggled into and out of Yemen and that he had hoped to reach the country’s capital to make government-level connections, the affidavit says. He was ultimately unable to make it to Sanaa, the FBI said.

The FBI says investigators began looking into Ellaboudy after learning that he had purchased precursor chemicals commonly involved in the construction of homemade explosive devices, including acetone and sodium bisulfate, as well as parts used for drones.

During the course of the investigation, the FBI says, he communicated with multiple informants – including one who purported to be a Houthi colonel – and provided advice and assistance on communications equipment.

Ellaboudy is charged under a law that makes it a crime to provide material support to a group designated by the United States as a foreign terrorist organization, of which the Houthis are one.

“These allegations are so deeply disturbing that they almost defy imagination,” John Eisenberg, the assistant attorney general in charge of the Justice Department’s National Security Division, said in a statement.

If convicted, Ellaboudy faces up to 20 years in prison, the Justice Department said.