He didn't get into the museum. So Drudge's image of the Mona Lisa is a bit hysterical.
It's not as if the man were slashing masterpieces (or tourists). Still, of course, it's bad. It was utterly squelched by soldiers (why were there soldiers at the museum?). Over a thousand people were inside and (if I'm reading this article correctly) aware that there was a terrorist attack in progress.
Donald Trump was immediately on it, Twitterwise:
'A new radical Islamic terrorist has just attacked in Louvre Museum in Paris. Tourists were locked down. France on edge again. GET SMART U.S.'