The small aircraft that landed on the Capitol grounds flew too low to be detected by security systems, the head of the Department of Homeland Security (DHS) said Thursday.
DHS Secretary Jeh Johnson said the lightweight gyrocopter, piloted by a U.S. mail carrier protesting the influence of money in politics, "apparently literally flew in under the radar," The Associated Press reported.
Johnson said he's awaiting the results of an investigation before weighing in on the possible need to tighten security measures around the nation's capital.
"I want to know all the facts before I reach an assessment of what can and should be done about gyrocopters in the future," Johnson said, according to the AP.
Piloted by Doug Hughes, a 61-year-old postman from Ruskin, Fla., the gyrocopter took off from southern Pennsylvania and flew several hours before landing on the Capitol's West Lawn Wednesday afternoon.
Capitol Police quickly detained Hughes, and the aircraft — deemed harmless by a bomb squad — was hauled away within three hours of the landing. But the episode has raised plenty of questions about how a rogue aircraft could travel through restricted airspace and land on the Capitol grounds without interception.
Sen. Ron Johnson (R-Wis.), chairman of the Senate Homeland Security and Governmental Affairs Committee, said he's launching an investigation.
"I am deeply concerned that someone has the ability to fly for over an hour through the most restricted airspace in our country, past the White House, and land on the lawn of the Capitol," Johnson said Thursday in a statement. "I am investigating this incident and I am requesting a full accounting by all federal organizations entrusted with securing the United States from this and similar events."
Rep. Martha McSally (R-Ariz.), a retired Air Force colonel and member of the House Homeland Security Committee, echoed those concerns Thursday.
"Although he was harmless, it identifies a vulnerability that if somebody wanted to do harm, they could get as far as he did," said McSally, who chairs the committee's subpanel on Emergency Preparedness, Response and Communications. "That makes me deeply concerned. … It highlights a vulnerability that we need to address very quickly."
Still, other top lawmakers seemed to downplay the significance of the incident, hailing the Capitol Police's response to the unprecedented incident.
"They have to deal with a new variety, and new levels, and new types of technology challenges to the Capitol. I have every faith in their ability to do so," Rep. Steve Israel (N.Y.), the head of the Democrats' messaging arm, said Thursday.
"You have to judge the totality of the situation. It was safe; the Capitol Police made certain judgments, and the situation was quickly contained and defused," he added. "We can always second-guess what they should have done [and] when they should have done it, but … when all was said and done, they did the right thing, and they ensured a swift return to safety and security on the Hill."
Johnson said the DHS is focused on staying "one step ahead of every incident like this" while being wary not "to overreact" in ways that would stifle certain freedoms.
"We are a democracy," Johnson said, according to the AP. "We don't have fences around our airspace, so we've got to find the right balance between living in a free and open society and security and the protection of federal buildings."
— Scott Wong contributed to this story.