An associate professor of philosophy at the University of Toronto is coming under heavy fire online today after tweeting on September 11 that the U.S. was "having its dumb little annual pity party again."

Jonathan Weisberg, an accomplished academic with dozens of published works and a PhD from Rutgers, published the tweet in question at 6:23 a.m. on the 20th anniversary of the world-changing 9/11 attacks.

It wasn't long before Americans and Canadians alike started going after Weisberg for his perceived insensitivity about what remains the deadliest non-state terrorist attack in recorded human history.

@jweisber I lost a friend in the Towers. I wept all day for the thousands who died as I watched people literally dive out of the towers to escape a death in hell’s fire. My heart still aches for all who died and lost. Not to mention the other souls lost in the planes. Go to hell pic.twitter.com/eY9ylrZoDw

— JeremyInAkron (@AkronJeremy) September 13, 2021

Another Canadian prof, Gad Saad of Concordia University in Montreal, retweeted Weisberg's message that same afternoon, at which point it started gaining traction — and causing friction — south of the border.

"Note that the butchering of 3,000 innocent people does not trigger this hero's ire," wrote Saad, himself no stranger to controversial views or problematic tweets. "What an execrable cretin."

Weisberg deleted the tweet in light of the enormous backlash, but it had already been screenshotted and shared widely on the social network.

@jweisber Why did you delete the tweet…… These people are sick. pic.twitter.com/Zi2xaNUpsF

— LoneWolf🐺 (@NxtLevelPatriot) September 13, 2021

As of Monday, the U of T professor's Twitter account has been set to private, but people continue to tweet to and about him at a rate of every couple of minutes. Some Americans appear to be tweeting threats. Others are calling upon U of T to fire Weisberg for his remarks.

"This tweet by Prof. Jonathan Weisberg is offensive and insensitive. A friend died in those attacks, and his widow/children still grieve. Totally unacceptable," wrote one Twitter user, tagging U of T. "He should be released from the university. Will you do the right thing?"

"How morally bankrupt do you have to be to tweet something like this? Shame on you, Jonathan Weisberg," wrote another. "This is beyond the pale."

You should be humiliated that this man tweets such insensitive shit on the anniversary of 3,000+ lives lost with YOUR UNIVERSITY in his bio! pic.twitter.com/Rvz5HEam0c

— Rae W.S. (@HoneyPinot) September 12, 2021

"Shame on U of T for maintaining employment of this professor," wrote another commenter still. "Academic freedom is critical but its clear that Jonathan Weisberg is a hateful person of irredeemable character. He's not suitable to teach students let alone to serve customers at a Starbucks."

Weisberg has yet to respond to a request for comment from blogTO, but a University of Toronto spokesperson did confirm on Monday that the administration is aware of the controversial tweet.

"As a leading global public research university, we have a long-standing commitment to freedom of speech and academic freedom," said the spokesperson in a statement to blogTO. "All members of our community are bound by Canadian and provincial law."