If U.S. officials and the media can be believed, America faces an epidemic of “homegrown” terrorism. Yet from U.S. Army shooter Nidal Hasan to would-be Times Square bomber Faisal Shahzad to so-called Christmas tree bomber Mohamed Mohamud, all of these mass murderers or potential mass murderers believed they were working on behalf of a foreign organization.

In the cases of both Mohamud and would-be Baltimore bomber Antonio Martinez, FBI officers caught the suspects by presenting themselves as members of an international terror network, not a group of Americans who had decided on their own to kill fellow citizens. “In the Portland plot, Mohamud believed he was receiving help from a larger ring of jihadists as he communicated with undercover federal agents,” a law enforcement official told the Associated Press, and Martinez’s FBI handler claimed to be “an Afghani brother.”

Authorities arrested Mohamud, a Somali-born naturalized American citizen, in Portland, Oregon, at a Christmas tree lighting ceremony in late November. He thought he was setting off explosives in his van, and hoped to kill hundreds of celebrants. In fact, the explosives were duds, provided by the FBI.

As the AP reported, a law-enforcement official told journalists that “Mohamud hatched the plan on his own and without any instruction from a foreign terrorist organization, and he planned the details, including where to park the van for the maximum number of casualties.”

Yet Mohamud had come to the attention of the Bureau when he was found to be in e-mail contact with an associate in the Afghanistan/Pakistan border region. -- The Feds thought he was trying to go there to train for jihad.

Indeed, the very success of these FBI sting operations demonstrates that the “homegrown terrorist” meme is often a myth. All these men, and scores more like them, think of themselves as members of a jihadi army waging war against the United States. It is very hard to find a case of an American citizen who became radicalized by other Americans, and then tried to unleash violence in America.

We saw a similar pattern following the arrest of a would-be bomber in Baltimore in early December. Federal law-enforcement officials said Antonio Martinez, who called himself Muhammad Hussein, was “acting on his own, without direction from any outside terrorist group.”

Yet Martinez chose a famous foreign name for himself: “Muhammad Hussein” is the name of the radical Shi’ite Ayatollah Fadlollah, who served as spiritual guide of the Lebanese Hezbollah movement largely funded by Iran. And in case after case, the “homegrown terrorists” certainly believed that they were in cahoots with overseas terror masters.

In most cases, there is clear evidence -- provided by the same officials who tell us the terrorists were entirely “homegrown” -- that attackers have been inspired or even guided by foreign leaders, either through direct contact, telephone conversations, or e-mail.

The case of Faisal Shahzad, the Times Square terrorist, highlights the extent to which the “homegrown” label is often misleading. Shahzad is an American citizen, but he told his trial judge that he had falsely sworn an oath to this country, and the prosecutor noted that Shahzad’s case blurs the line dividing “homegrown” and “foreign terrorists,” since he was trained in Pakistan to operate in the United States.

And what of Nidal Hasan, the Army officer who killed 13 people at Fort Hood? He was radicalized in America, but his guru was apparently Anwar al-Awlaki, who worked in America for several years, guided two of the 9/11 killers, and who, in the view of terror expert Evan Kohlmann, played a similar role “in numerous ‘home grown’ terrorism cases in the United States and Britain.”

Journalists should challenge government officials to prove that terrorists do not think they are acting as members of an international jihadi network. To insist that terrorists are nothing but angry, radicalized Americans is an act of willful blindness, and it makes it more difficult for us to combat the terror masters and their foot soldiers among us.

Michael Ledeen is a senior fellow at the Foundation for Defense of Democracies.