The Wall Street Journal reports: Islamic State sent at least three Belgians who had joined its ranks in Syria back to Europe in 2014 to carry out an attack that was narrowly foiled, according to evidence revealed Monday by Belgian judges at the start of a trial involving at least 16 people implicated in the plot.

The plot appears to foreshadow the Nov. 13 attacks in Paris: The men were taking orders from a man they called Omar, the judges said, identified by authorities as Abdelhamid Abaaoud, the Belgian Islamic State operative who led the group that attacked Paris.

The alleged plot, whose target is unclear, was foiled in January 2015, when elite Belgian and French police killed two of the men at a safe house in the eastern Belgian town of Verviers and arrested several others.

Authorities failed to catch Mr. Abaaoud, allowing him to rebuild his network in Europe for the terror attacks he orchestrated in Paris in November.

The judges presented evidence at the start of a three-week trial in the Brussels courthouse. Nine of the defendants weren’t present: They are believed to be fighting in the ranks of Islamic State in Syria or, authorities fear, back in Europe.

Belgian security services had been listening to the men’s telephone calls after discovering that one of the defendants—, Souhaib El Abdi, who authorities allege has numerous connections to known Islamist radicals in Belgium—had recently returned from a brief stay in Turkey, suggesting he may have gone to Syria, the judges said.

“I was there on vacation,” Mr. El Abdi said Monday at the trial.

Prosecutors labeled four of the men on trial as leaders of the plot. Among them are Mr. El Abdi, Mohammed Arshad Mahmood Najmi, a former tram driver in the Brussels transport system, and Marouan El Bali.

Mr. Najmi has admitted to spending several weeks in the ranks of Islamic State in September 2014, his lawyer says. He has told police interrogators that an Islamic State commander sent him back to Europe to carry out an attack, according to people familiar with his testimony. [Continue reading…]