Bomb plot: When should authorities have stepped in?

It is a crucial question in terrorism cases: When should the government step in and make arrests?

If US law enforcement waits for bombs to be made, it may act too late, and innocent people could be hurt. If it acts too soon, it may not have an airtight case, or maybe any case at all.

In its latest terror arrests, involving three men born in Afghanistan, the government seems to have decided it was riskier to not act, say some terrorism experts. After all, the UN General Assembly is preparing to meet in New York this week, followed by the Group of 20 summit in Pittsburgh. Any terror incident would instantly gain world attention.

In fact, one of the defendants was on his way to New York just before Sept. 11.

"The critical issue is, when should the government intervene and intercept?" says Carl Tobias, a law professor at the University of Richmond in Virginia who follows terror investigations. "In all cases, it's a different calculus."

For example, in May of this year, the New York Police Department arrested four men – three of them Muslim converts, according to the Associated Press – as they allegedly tried to plant a bomb at a synagogue in the Bronx. The supposed bomb was actually an FBI-altered device, and the men's defense attorneys are claiming entrapment. The case is pending.

On the other hand, two years ago, the government arrested six men who intended to attack Fort Dix in New Jersey with assault rifles. That plot was still in the planning stages. The case went to trial in October 2008, and all men pleaded guilty or were convicted.

In contrast with US law enforcement, British authorities have been willing to let plots more fully develop before moving against suspects, says Daveed Gartenstein-Ross, terrorism expert and vice president of research at the Foundation for Defense of Democracies.

"Britain has had far more prosecutions for actual terrorism plots," he says. However, he notes, the threat there has become more imminent.

In the latest US terror case, Mr. Tobias says, it appears the government felt it had to act because of concerns that some of the defendants, or perhaps others, were beginning to make bombs. One of the defendants, Najibullah Zazi, has reportedly admitted receiving weapons training from Al Qaeda. He is alleged to have bombmaking instructions on his laptop computer. He and his father, Mohammed Wali Zazi, were arrested Saturday in Denver. Both were charged with lying to federal agents.

However, the younger Mr. Zazi had apparently been tipped off that the FBI was asking questions about him. The person supplying the tips was Ahmad Wais Afzali, an imam in a Queens mosque – something that even Mr. Afzali's lawyer, Ron Kuby, acknowledges.

"The government felt it had to move," Tobias says. "Its hand was forced, and there was no point in keeping it secret anymore."

On Monday, the government arraigned Afzali, who immigrated to the United States in 1981 when he was 8 years old. The government claims he lied to federal agents when he said he had not informed Zazi that the FBI was asking questions about him and that his phone calls were being monitored.

On Monday, outside of the federal courthouse in Brooklyn, Mr. Kuby maintained Afzali's innocence.

The imam did know Zazi for many years, Kuby says. And the lawyer does not deny that the imam told Zazi the FBI was asking questions about Zazi and that the imam knew his own his conversations were being taped.

"So why in the world would the imam lie to the FBI about the contents of a conversation that he knows is being taped by the FBI?" asks Kuby. "It would be as though in this interview, I turned around and said, 'I never gave that interview.' "

• Michael B. Farrell contributed to this report from San Francisco.

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For more information on the current terror case, click here.

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