The document filed by federal prosecutors says Ahmed Mohamed expressed pleasure in a handwritten note that 4,000 U.S. troops had died in the Middle East, the St. Petersburg Times reported Wednesday.
Assistant U.S. Attorney Jay Hoffer called Mohamed's note "the coldest statement of this defendant and the most telling as to his hatred and disdain for the United States."
Mohamed also called the United States a "vile nation," the memo said.
The former University of Florida student was arrested along with Youssef Megahed, 22, last year after low-grade explosives were found in the trunk of their car.
Prosecutors said they hope U.S. District Judge Steven Merryday will take their memo into consideration before sentencing Mohamed Friday.
Mohamed faces a maximum of 15 years in prison.
Megahed's trial has been delayed.
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