A 23-year-old former Marine Corps reservist accused of shooting at the Pentagon and other military-related buildings in late 2010 has pleaded guilty to three counts on Thursday.

Yonathan Melaku agreed to a 25-year prison sentence. If Melaku had been convicted on all the federal charges, he could have faced a maximum life sentence.

The U.S. government accused Melaku of shooting at the Pentagon, the National Museum of the Marine Corps and a Coast Guard recruiting center in northern Virginia. Melaku pleaded guilty to injury to property of the United States by shooting with a firearm, using carrying and discharging a firearm during a crime of violence and attempted injury to veterans' memorials.

Melaku attempted to flee law enforcement back in June 2011 when they found him trespassing in Arlington National Cemetery, but he was apprehended. He discarded a backpack in which police found 9mm casings, numerous Arabic statements referencing al Qaeda, along with Ziplock bags containing ammonium nitrate, according to a police affidavit.

It was disclosed Thursday that Melaku's intention was to spray-paint grave markers with Arabic statements.