North Korea threatened to shoot down U.S. reconnaissance planes flying off its east coast this week, and while it may seem like empty bluster, a look at history shows that it has taken down American aircraft before — and in the process provoked Washington to even consider nuclear strikes.

On April 15, 1969, a North Korean MiG-21 opened fire on a U.S. Navy EC-121 reconnaissance plane off the east coast of the peninsula, resulting in the deaths of 31 Americans.