As tensions between Washington and Pyongyang rose, Gen. Vincent Brooks, the top American military commander in South Korea, said in a statement Wednesday that the U.S. and South Korea are prepared to go to war with the North if given the order.

“Self restraint, which is a choice, is all that separates armistice and war,” Gen. Brooks said. “We are able to change our choice when so ordered.…It would be a grave mistake for anyone to believe anything to the contrary.”

Earlier in the day, allied armies conducted a rare live-fire drill, launching tactical surface-to-surface missiles off the east coast of Korea—an action they said was aimed directly at “countering North Korea’s destabilizing and unlawful actions on July 4.”