The Wall Street Journal reports: An Islamic State operative suspected of helping plan the Paris attacks had been monitored in Syria by Western allies seeking to kill him in an airstrike, but they couldn’t locate him in the weeks before the plot was carried out, two Western security officials said.

The operative, a Belgian citizen named Abdelhamid Abaaoud, was convicted in absentia in Brussels earlier this year of recruiting jihadists, was suspected of masterminding a foiled plot to behead police officers, escaped to Syria and was profiled in Islamic State’s online magazine mocking European authorities for their failure to catch him. A year ago, video emerged of him in Syria, smiling as he drove a truck dragging the dead bodies of Islamic State’s opponents tied to the bumper.

Mr. Abaaoud is one of two people who have emerged at the center of a probe into the attacks that killed 129 people on Friday. Both are at large. French and Belgian authorities are also searching for a 26-year-old petty criminal named Salah Abdeslam, who they say rented a car used in the attacks on Friday and is suspected of driving some of the suicide bombers through Paris.

On Monday, dozens of masked Belgian police stormed a house in a predominantly Muslim district in Brussels in their hunt for Mr. Abdeslam.

French prosecutors said police had stopped Mr. Abdeslam and two other men on their way to Brussels just hours after the Friday massacre. But a roadside background check failed to show that Mr. Abdeslam had rented a car in Belgium that was found outside the Bataclan night club, the site of one of the attacks, and police let him go. [Continue reading…]