In "The bridge on the river kwai" why did United States Navy Commander Shears want to destroy the bridge?

It was a Japanese bridge and the Japanese were the enemy. He understood Col. Nicholson's motivation in showing their Japanese captors that the British were superior at engineering, but since their skills and efforts were effectively being used to help the war effort of their Japanese enemies, Shears thought Nicholson's actions bordered on either treason or lunacy.