"Three teams of Islamic State attackers acting in unison carried out the terrorist assault in Paris on Friday night..."

"... including one gunman who may have traveled to Europe on a Syrian passport along with the flow of migrants," the NYT reports.

The Paris prosecutor, François Molins, said the attackers were all armed with heavy weaponry and suicide vests.... The gunman with the Syrian passport — which Greek officials said had been registered at the Aegean island of Leros on Oct. 3 — was 25, and died at the stadium. Another gunman, who died at the concert hall, was 29 and a native of Courcouronnes, about 20 miles south of Paris. He had a criminal record and was known to be associated with extremist Islamic ideology, Mr. Molins said....

The possibility that one of the attackers was a migrant or had posed as one is sure to further complicate the already vexing problem for Europe of how to handle the unceasing flow of people from Syria, Iraq, Afghanistan and elsewhere. It could also lend weight to the xenophobic arguments of right-wing populists like Marine Le Pen, the leader of the National Front party, who on Saturday held a news conference to declare that “France and the French are no longer safe.”