A terror suspect in our midst

It's difficult to know whether to feel more alarmed or relieved by the news that the FBI today arrested a man who they say intended to detonate a car bomb outside a military recruiting station in Catonsville. As in a case in Portland, Ore., in which a young man has been charged with trying to blow up a Christmas tree lighting ceremony, officials say they had been tracking the suspect in the Catonsville case, a recent convert to Islam named Antonio Martinez, and had provided him with bogus explosives that posed no harm to the public. Are we to marvel that the FBI apparently got its man, or to tremble at just how frequently — and close to home — it is being tested?

For all our focus on waging the war on terror in Afghanistan and Iraq, in the mountains of Eastern Pakistan and in the deserts of Yemen, we seem to face a constant stream of threats from would-be terrorists in our midst. Federal authorties have been successful in a string of cases like this one; at least 15 times in the last two years, the FBI has foiled plots, often by penetrating the scheme and orchestrating the results.

But officials have not always picked up on the warning signs, such as in the shootings at Fort Hood in which Nidal Hassan, an Army psychiatrist under the sway of a radical (and American-born) Islamic cleric, is accused of killing 13 and wounding 30 more. The same is true in the case of Faisal Shahzad, a naturalized American citizen who lived a seemingly normal life in Bridgeport, Conn., until he attempted to blow up a car in Times Square — a plot that might well have succeeded if not for a quick response from street vendors who sensed something amiss.

It has been nine years since the Sept. 11 attacks, and the fact that we have not suffered nearly so devastating a blow since then gives little comfort. We have avoided attacks because the perpetrators were unable to pull them off — such as alleged underwear bomber Umar Farouk Abdulmutallab — or because of intelligence tips that came just in time, as in the bombs disguised as printer cartridges sent to Chicago synagogues. But how long will it be before our luck runs out?

The criminal complaint against Mr. Martinez says that an FBI informant spotted disturbing postings on his Facebook page in September and struck up an association with him. The complaint alleges that Mr. Martinez said he wanted to harm military personnel and had targeted the Catonsville recruiting station. The informant went on to have a string of recorded conversations with the suspect over the next several weeks.

The transcripts included in the complaint come across as crazed rants and childish revenge fantasies that he could wage a one-man war against the entire U.S. military. The FBI says Mr. Martinez had elaborate plans to climb into the recruiting center from the roof and, after killing all inside and making his escape, to set up a clandestine camp in the woods where he could make his last stand. The transcripts say that he joked about blowing up Andrews Air Force Base and killing all American soldiers he saw anywhere. It sounds ridiculous.

But the description of the plot that unfolded after the FBI's informant got him in touch with another agent posing as an Afghan jihadist is heart-stopping. Just this morning, a few miles from downtown Baltimore, FBI agents observed Mr. Martinez meet with his supposed co-conspirators, inspect and arm what he believed to be a bomb in the back of an SUV, drive it in front of the recruiting center and then retreat to a vantage point, where he pushed a button that he had been told would make the bomb explode. Those last paragraphs of the criminal complaint are simply terrifying. It takes a moment, after reading them, to remember that the suspect was in the FBI's hands the whole time, that no one was in danger.

But what about next time? What about the next wannabe terrorist who can figure out how to build a bomb without anyone's help, or who hatches a plot with someone who's not recording the whole thing for the FBI?

If there is anything comforting about this episode, it is not the FBI's skill in reeling its suspect in. After all, their success here and in Portland may make it that much more difficult for agents to gain the trust of would-be jihadists (in fact, Mr. Martinez nearly backed out after reading about the case in Oregon). What is comforting is the reluctance of everyone else Mr. Martinez approaches to participate in his plot. He allegedly tried to recruit others, and they turned him down. One told him that what he wanted to do was wrong and would be harmful to Muslims. When he posted on Facebook that we "were born in order to die," someone replied to remind him of the "balance in Islam." Similarly, agents first began tracking the Portland bomb suspect after someone grew concerned about him and tipped them off.

Some will no doubt use these attempted attacks to reinforce their prejudice against Islam. But ultimately, it is the nation's Muslims who have the greatest power to protect us from homegrown terrorists. As much as we rely on the daring of the FBI to keep us safe, we may owe the most to peace-loving Muslims who will not tolerate the radicals in their midst.