On Christmas Day 2009, Umar Farouk Abdulmutallab nearly succeeded in murdering almost 300 civilians aboard Northwest Flight 253. As the plane approached its final destination of Detroit, Michigan, Abdulmutallab was seen entering the lavatory, returning to his seat, and placing a blanket over his head. Moments later, passengers noticed a burning smell and smoke emanating from his seat. As Abdulmutallab attempted to detonate explosives inside his underwear, passengers leapt onto the would-be terrorist and prevented him from accomplishing his sinister ambition.

The journey that led Abdulmutallab to Flight 253 navigated multiple destinations, including a stint in Yemen, where he obtained both training and direction from Anwar al-Awlaki, the American-born al-Qaeda cleric killed in a U.S. drone strike last year.

Upon concluding his training with al-Qaeda, Abdulmutallab attempted to execute his act of terror aboard that Christmas Day flight in 2009. Thanks to the quick action of passengers on board, Abdulmutallab’s failure landed him into the custody of American law enforcement.

Just over two years later, the saga of Umar Farouk Abdulmutallab’s failed attempt at martyrdom came to a conclusion.

Earlier this week, U.S. District Court Judge Nancy Edmunds sentenced Abdulmutallab to life in prison. She noted that the sentence was a just one: “The defendant poses a significant ongoing threat to the safety of American citizens everywhere.”

Not surprisingly, Abdulmutallab showed no remorse upon hearing his being condemned to a life behind bars. He spoke before the court, stating, “Mujaheddin are proud to kill in the name of God. And that is exactly what God told us to do in the Koran. Today is a day of victory.”

The case of the underwear bomber shows the extent to which terrorists will go to strike at America. As U.S. intelligence and law enforcement capabilities adapt to the malleable threat of terrorism, new and unique targets—and unconventional methods for attacking them—will surely arise.

This reality portends the need for adopting a priori assumptions related to the next threats sure to face the American homeland.

As always, irrespective of the threat, a vigilant and informed public will likely prove the deciding factor in whether or not an act of terrorism, once operational, will be successful. Thankfully, in the case of Umar Farouk Abdulmutallab, vigilant citizens put a stop to his terrorist inclinations and subsequently landed him a life sentence in federal prison.