President Barack Obama called it "an attack on all humanity" and said the United States stood ready to support France in doing whatever was necessary to bring the perpetrators to justice.
Germany's Chancellor Angela Merkel confined her comments to sympathy for the victims, their families and all residents of Paris.
If the murderers were found to be agents of jihadism, it will be a setback to Merkel's attempt to open European doors to more refugees from Syria and Afghanistan.
That would be the wrong international response. If this is another co-ordinated act of jihadism like 9/11, it demands more than defensive precautions like closing borders or beefing up internal security.
It is time for a serious international security operation in Syria and Iraq to rid those countries and the world of the menace that was so quick to celebrate the Paris attacks.
This time the US should not be almost alone, and should not need to take the lead yet again. France has shown the capacity to take decisive military action in the North African territory where this scourge has appeared.
France was united in its condemnation of the Charlie Hebdo attacks, and this one is much worse. Not only were there multiple targets but they were in public places - a concert hall and a sports stadium - and this time the victims had done nothing that could be called provocation or an insult to Islam.
This was cold-blooded murder, a mass killing carried out methodically in the concert hall.
When combined with simultaneous attacks on restaurants and the stadium, it was designed to terrorise a city and make a statement about the resources and organisation of those who are prepared to massacre innocent people in their sick religious medievalism.
The time for anger and hand-wringing in the West has passed.
If the United Nations Security Council still cannot get its act together, France and all Western allies need to take firm action to cut this cancer out.
Debate on this article is now closed.
