Though Judge Richard McGregor-Johnson described Islam's plans as "vague and unlikely to succeed," he said the Belfast-born convicted fraudster presented a danger to the public.
"I would have wished to consider an extended sentence," he said. "But the authorities are clear, even if a court finds that the person does represent a danger to the public, that doesn't justify a longer sentence."
Islam said he didn't want to kill people, but believed the 29-year-old prince, who has served in Afghanistan as a member of the British Armed Forces, had "blood on his hands."
Police found documents on his computer that read, “Aim for target. No civilians to be injured. Dress code is the the biker look. Use low-calibre pistol at close range. Not to be viewed as Islamist extremist.”
Islam, a convicted fraudster, converted and changed his name in 2010. He visited Egypt and Thailand before flying to London in May of last year. Feeling "scared and nervous" about his plans to kill Harry, Islam went to a Hounslow police station the day after he arrived.
He told a police officer about his plans to kill someone.
"The PC called a sergeant and counter terrorism officers. Islam was asked which particular person he intended to kill. It was at this point he said Prince Harry. He said he intended to kill Prince Harry tomorrow," a prosecutor told the court.