Attack on Paris: what you need to know about the terrorist assault on the French capital.

• Author: Smith, Patricia
• Position: INTERNATIONAL

On the night of November 13, Paris was rocked by a series of coordinated terrorist attacks that killed at least 129 people and injured more than 350. It was the worst bloodshed on French soil since World War II (1939-45).

The brunt of the massacre took place at a concert given by the U.S. rock group Eagles of Death Metal. Gunmen with assault weapons stormed the concert hall, firing into the crowd and taking hostages. Suicide bombers and shooters struck several other sites, including restaurants and outside a soccer stadium.

The attacks came less than a year after terrorists in Paris killed 16 people, including 12 at the office of the satirical French newspaper Charlie Hebdo (see "Terror in Paris," Upfront, Feb. 23, 2015).

Here's what you need to know about the attacks and what they mean for France, the U.S., and the world.

1 Who was behind the attacks?

The terrorist group ISIS immediately claimed responsibility. ISIS (the Islamic State of Iraq and Syria) is a radical Sunni Muslim group that has taken over large parts of Syria and Iraq since 2014 and imposed strict Islamic law. ISIS has beheaded several Western journalists and Christians and used a sophisticated online campaign to recruit tens of thousands of fighters to wage jihad (holy war).

Authorities say three teams of terrorists carried out the Paris attacks. Seven attackers were killed that day, either by their own suicide bombs or by French police. Most of the suspects were either French citizens or had grown up in France or Belgium. The attacks are the biggest that ISIS has carried out in the West.

2 Why wasn't the plot detected?

American and European intelligence officials thought ISIS was planning an attack in France but didn't have specifics. "We did not have enough information to take action to disrupt it," one official said.

France has had trouble keeping tabs on would-be terrorists within its borders. ISIS and other groups have had success recruiting in the ghetto-like suburbs of Paris, where many of France's 5 million Muslims live. There's high unemployment and deep resentment at feeling segregated from the larger society.

Europe's migrant crisis is complicating the security situation: Hundreds of thousands of refugees, many fleeing the war in Syria, have flooded into Europe in recent months. News that one of the bombers may have entered France through Greece, along with the migrants, seemed to confirm fears that terrorists could be slipping in undetected among the refugees.

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