Weapons used by the Bataclan in Paris (France) and Brussel (Belgium) terror attack came from a weapon supplier from Rotterdam (huge cargo port also) in The Netherlands. Investigations in France have several names of Dutch weapon suppliers. They also found some fingerprints of Dutch people. They have been arrested and already released by the lack of evidence.
The weapons came from Slovakia and were smuggled to The Netherlands where it was stored and picked up by the Brussels and Paris terrorists.
Some of the weapons came from Operation Fast and Furious