What was the hardest sniping assassination in the world?

Without a doubt, the assassination of U.S. President John Fitzgerald Kennedy was probably the hardest sniping assassination in the world, and why that is being said is because of the many that have been accused in the killing.

There are still no solid answers to this day, only countless conspiracy theories, even though Lee Harvey Oswald was convicted for the shooting. Oswald maintained his innocence. Though numerous have been accused in the past ranging from the FBI to Cuba to CIA to the USSR. Many still think there were conspiracies amid these listed groups.