Adam Gadahn is not a lobbyist. Yet his recent commentary should have a profound impact on important U.S. policy.

Mr. Gadahn is an American-born al-Qaida operative who has grown impatient with his fellow jihadists for their failure, in his view, to adequately bring mayhem to the streets of America. It's doubly frustrating for the young traitor.

"America is absolutely awash with easily obtainable firearms," he said in a recent video. "You can go down to a gun show at the local convention center and come away with a fully automatic assault rifle without a background check and, most likely, without having to show an identification card. So what are you waiting for?"

Actually, Mr. Gadahn doesn't give his followers enough credit. According to the Government Accountability Office, terror suspects have managed to purchase guns and explosives in the United States more than 1,300 times since 2004.

At the same time, he might be slightly optimistic. Gun show rules aren't as uniformly loose as he seems to believe, even though it is indeed extraordinarily easy to obtain weapons at them.

Congressional Republicans fuel his optimism, though. They repeatedly have blocked amendments that would make it illegal to sell a weapon to someone on a terrorism watch list. So in the United States, such a person couldn't get on a plane out of the country, but could buy a high-capacity firearm inside the country.

Several bills are pending that would expand the federal background check system to cover private sales at gun shows and to outlaw gun sales to people on terrorism watch lists.

Neither measure would preclude any legitimate citizen from buying or owning a firearm. They simply recognize the fact that firearms sales are a matter of national security.