Dina Temple-Raston

Life changed as Sadiik Yusuf knew it about two years ago, when the FBI appeared at his front door in Minneapolis to tell him his son Abdullahi had been stopped at the airport, suspected of trying to board a flight that would take him to Syria to fight with ISIS.

Danny Nolan was the first man to swing a wrecking ball in Manhattan in 25 years. Wrecking balls hadn't been allowed on the island for a very simple reason: The buildings are much too close together to allow a huge ball to swing back and forth.

An exception was made for Nolan because he, and the other construction workers of the International Union of Operating Engineers Local 14, were "working the pile" — hauling away what was left in the World Trade Center towers after the Sept. 11 attacks.

The man who fatally shot five police officers in Dallas may have had plans for a wider attack, the city's police chief said Sunday. Dallas Police Chief David Brown provided new details about the tense two-hour standoff that police had with the gunman before he was killed.

"We're convinced that this suspect had other plans," Brown told CNN, adding that the shooter "thought that what he was doing was righteous and believed that he was going to target law enforcement and make us pay for what he sees as law enforcement's efforts to punish people of color."

All eyes were on 20-year-old Abdullahi Yusuf when he stepped on the stand in federal court last week in Minneapolis to testify for the prosecution in America's largest ISIS recruitment trial.

As Yusuf began to speak, his words provided a rare, behind-the-scenes look at how more than a dozen young men convinced themselves that the way to prove they were good Muslims was to travel to Syria and fight for ISIS.

In a Minneapolis federal courtroom, three Somali-Americans are on trial for allegedly plotting to join the Islamic State in a case that's expected to offer the most detailed public accounts yet of how the extremist group recruited nearly a dozen young men from the Twin Cities.

Imagine this scenario: A young Muslim leaves home to travel to Syria to join ISIS. Thousands of young men from Europe have done exactly that in the past two years.

But here's the twist: Imagine that just weeks after arriving, the young man realizes he's made a terrible mistake. What does he do now?

Nearly all of the men implicated in last week's attack in Brussels and the November rampage in Paris have something in common – they are ex-convicts.

When 30-year-old Edward Archer opened fire on a Philadelphia policeman earlier this month, he quickly offered authorities a motive: He told them he had done it for the Islamic State.

"He pledges his allegiance to the Islamic State," Capt. James Clark of the Philadelphia Police Department told reporters hours after the Jan. 7 shooting. "He follows Allah and that is the reason he was called upon to do this."

The FBI, for its part, has said it is investigating the attack as a possible act of terrorism — inspired by ISIS.

Editor's note: This story ran originally on Dec. 2, 2015. It has been updated to reflect this week's bombings in Brussels.

When police announced that Khalid el-Bakraoui and his brother, Ibrahim, had blown themselves up in two separate attacks in Brussels on Tuesday, the pair became the latest example of terrorists who share fraternal bonds.

If you walk along the shopping streets of Paris, you could be excused if you thought the city had somehow managed to put last week's terrorist attacks behind it.

Along Boulevard Haussmann, children bundled against the cold climb small platforms to gaze, nose-to-glass, at the Christmas windows of the Printemps department store. The sidewalks are crowded, and the city's holiday shoppers appear to be arriving in droves.

The terrorist attacks in Paris on Friday could be an early harbinger of a new, more professional kind of terrorist attack leveled against the West.

In the past, al-Qaida depended on violent jihadis showing up in Pakistan or Yemen with a passport or visa that would allow them to return to home. The group would train them and send them back. Counter-terrorism officials are concerned that ISIS has taken that a step further by sending battle-hardened fighters to do their dirty work.