If these leaders are genuinely concerned about the victims of terrorism, where were they, for example, when Israel started massacring the civilians of neighbouring Gaza last September. About 2000 died in that 23-day outrage, but if there was any procession of appalled international leaders through Gaza's blighted streets, I missed it. To the contrary, they even marched alongside Israeli Prime Minister Benjamin Netanyahu and Foreign Minister Avigdor Lieberman in Paris.
As it happens, the victims in last week's assaults were killed by Russian-designed weapons, including the ubiquitous Kalashnikov assault rifle - of which there could be as many as 100 million in circulation around the world.
This was the weapon that killed the cartoonists. A weapon produced by Russian Technologies, a government-controlled state corporation. But that didn't stop Russian Foreign Minister Sergei Lavrov from brazening it out in Paris. Perhaps he saw it as a sales opportunity, like our Foreign Minister does when he rushes around the world selling butter and milk.
Just last month, Kalashnikov revamped its corporate image, rebranding itself with a new CK logo - standing for Kalashnikov Concern - and new slogans. The English version is "Protecting Peace". Chief executive Sergei Chemezov said he wanted the CK brand to become "as recognised and valuable" as Apple.
One marketing video lauded the AK-47 as providing "freedom movements" with the ability to "fight back against colonial armies ... [and] ... demand rights and achieve justice". Another showed Russian special forces using them to "liquidate" terrorists in the North Caucasus region, with the tagline "Kalashnikov promoting peace and calm".
With the world awash with deadly weaponry, and the Big Five, to say nothing of competitors like Germany, Italy and Israel - the newspaper Haaretz reports Israeli arms exports up from $2.5 billion in 2002 to $9.74 billion in 2013 - eager to sell or donate more, is it any wonder that any wannabe jihadist, or for that matter petty criminal, can arm themselves with ease.
More than 20 years ago, Amnesty International, Oxfam and other NGOs launched a campaign to have some form of regulation introduced to the trade in conventional weapons. Despite strong opposition from the arms dealer nations, the UN General Assembly overwhelmingly approved a global Arms Trade Treaty in April 2013.
By the end of last month, 60 of the 130 signatories had ratified it, 10 more than required to bring it into force. Britain, France and Germany have ratified it, the US has signed but the Senate is refusing to ratify. Russia, China, India and Pakistan have refused to sign or ratify.
Joining funeral marches won't stop terrorists. Making it harder for them to buy weapons would at least slow them down.