France's intelligence agency has foiled a plot to attack a military base in the south of the country, the French interior minister announced. Speaking at a press briefing Wednesday, Bernard Cazeneuve said that the General Directorate for Internal Security (DGSI) had arrested four men, ages 16 to 23, in dawn raids in different parts of the country.

According to a source close to the investigation, the men were planning to kidnap and behead a high-ranking army official in January 2016 — one year after the Paris terror attacks, in which gunmen killed 17.

"Statement by Bernard Cazeneuve tonight at Place Beauvau concerning the foiled plot."

French daily Le Monde reported that the youngest suspect, a 16-year-old boy, was later released, after the suspects admitted he had been left out of the plot because of his age.

The other three suspects revealed their plans during questioning and told investigators they were plotting to enter the Fort Béar national commando training center in the Mediterranean town of Port-Vendres, close to the border between Spain and France. Once inside the base, the men planned to behead a high-ranking officer and film the scene with a GoPro, with a view to broadcasting the footage online.

French authorities had been monitoring the suspects for months. Authorities are believed to have fast-tracked their arrests ahead of Bastille Day on July 14 — a day in which servicemen are recognized in celebrations across the country.

Having initially planned to announce the arrests Friday, the government brought the announcement forward by two days, when President François Hollande told journalists in the port city of Marseille that the government had "stopped terrorist attacks which could have taken place."

Cazeneuve was informed the president had made an announcement about the arrests while attending a leaving party for Paris police chief Bernard Boucault, and immediately convened an emergency press briefing to give a statement about the foiled plot.

Speaking to journalists Wednesday, Cazeneuve said that the "main instigator" of the plot was a 17-year-old first spotted by intelligence services for his "activity on social networks" and for his links to "French jihadists currently in prison." The young man had also been planning to travel to Jihadist-controlled territory in Syria.

The plot to attack the base at Port-Vendres was discovered after the intelligence agency tapped the man's phone following his interrogation.

Among his accomplices are a former marine — a leading seaman who trained at Port-Vendres before being discharged in 2015 for medical reasons. The third suspect, age 19, had known links to radical Islamist groups and was being monitored by police.

During his traditional July 14 address, Hollande sought to reassure the population, and said that enhanced security at France's public sites would remain in place until at least the end of the year. Some 10,000 troops are currently deployed around the country as France remains on high alert in the wake of the January terror attacks.

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