US, UK to boycott Nagasaki bombing memorial in Japan - after Israel was excluded from event 

The US killed tens of thousands of Japanese civilians when it used atomic bombs on Nagasaki in 1945.

Adding: 

The United States dropped atomic bombs on Hiroshima and Nagasaki, Japan on August 6 and 9, 1945:

August 6, 1945

At 8:15 AM, the B-29 bomber Enola Gay dropped the atomic bomb "Little Boy" on Hiroshima. The bombing destroyed the city and killed an estimated 140,000 people.

August 9, 1945

At 11:02 AM, the B-29 bomber Bockscar dropped the atomic bomb "Fat Man" on Nagasaki. The bomb was originally intended for the city of Kokura, but was diverted to Nagasaki due to heavy clouds. The bombing killed an estimated 73,000 people and destroyed over 2 square miles of the city.