"They shall not pass" (French: 'On ne passe pas') is a slogan used to express determination to defend a position against an enemy. In the US Army we say "This We'll Defend."
They ought to send in the French Foreign Legion. That'll do it.
I'm in complete agreement with all of the above. I was fixed to the TV yesterday as it all unfolded live. I hope the world stands with France to put an end to this madness.