The man convicted of killing 13 people in the 2009 rampage at Fort Hood, Texas, will face execution by firing squad on Dec. 3, according to the acting secretary of the U.S. Army.

In a social media statement, acting Secretary Adam Telle said the execution of Army Maj. Nidal Malik Hasan will occur at Fort Hood.

On Monday, Pentagon spokesperson Sean Parnell confirmed that President Donald Trump approved the sentence. The U.S. military has not executed a service member since 1961.

Hasan, an Army psychiatrist, walked into a base medical facility where soldiers were undergoing health checks, shouted “Allahu akbar” — Arabic for “God is great!” — and opened fire with a laser-sighted pistol. Thirteen people were killed and more than 30 wounded.

Attempting to stop soldiers from deploying to Afghanistan to kill fellow Muslims, he mounted virtually no defense at trial. He told jurors the evidence would confirm he was the gunman, calling himself a soldier who had “switched sides.”

While Trump’s approval sets procedural steps in motion, Hasan could halt them for years through a civilian federal habeas corpus appeal, according to a May article in Army Lawyer magazine.