It has been more than eight years since 9/11 and US authorities have managed to avert another big terror attack on American soil through improved intelligence — and luck.

Last night’s attack had eerie echoes of a foiled terror plot at Fort Dix in New Jersey in 2007 when six foreign-born men were charged with planning to assault the army base and kill scores of soldiers with automatic weapons and rocket-propelled grenades.

The six men — shopkeepers, cab drivers and pizza deliverymen — were caught because of a lucky break. A shopkeeper alerted the police to a disturbing video he had been asked to copy on to a DVD. He had watched the film, which showed ten young men shooting assault weapons at a firing range while calling for jihad and praising Allah.

After 15 months of surveillance, the men — who had all lived in the US for years, and two of whom held green cards — were arrested as they approached the final stages of their plan, which was to purchase the weapons to carry out the attacks.

Since the September 11, 2001, attacks, the US has undertaken a complete overhaul of its intelligence services, amalgamating them in the Department of Homeland Security. Channels of communication and information sharing were opened up between the FBI and CIA, a failure that contributed to the intelligence blunders before the attacks.

In addition, terrorist watchlists were activated for every flight into the US. Today, passengers are screened before an aircraft bound for America can take off. So successful have efforts been to keep out foreign terrorrists that US officials believe the greatest danger of an attack now comes from home-grown terrorists.

In recent weeks the FBI, using “sting” operations, claims to have thwarted several planned attacks, including one extremely serious case in which an Afghan-born airport van driver is accused of planning bomb attacks using hydrogen peroxide.

Najibullah Zazi was arrested after months of undercover surveillance — and a shop video showing him buying large amounts of hydrogen peroxide. Law enforcement officials allege that he attended an al-Qaeda training camp in Pakistan.

In another case Hosam “Sam” Smadi, a 19-year-old Jordanian living in Italy, Texas, and working at a roadside restaurant, was arrested on September 24. According to the Government, he tried to detonate what he thought was a huge truck bomb — it was a fake, provided by the FBI — in the parking garage under a Dallas skyscraper.

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