After North Korea demonstrated for the first time its ability to build a nuclear-capable missile capable of striking the US, U.S. and South Korean forces responded with a show of force by firing deep-strike, precision missiles into the sea.

After the dueling shows of military force by rival nations, Gen. Vincent K. Brooks, the commander of American troops in South Korea, gave a blunt assessment of the tense situation.

“Self-restraint, which is a choice, is all that separates armistice and war,” Brooks told the New York Times in reference to the Korean War, which ended with a ceasefire rather than a peace treaty in 1953.

“As this alliance missile live-fire shows, we are able to change our choice when so ordered by our alliance national leaders,” said Brooks, adding that it “would be a grave mistake for anyone to believe anything to the contrary.”

North Korea has often provoked the U.S., most recently by detaining a healthy U.S. student who was traveling through Pyongyang and releasing him back to the U.S. in a coma.

North Korea's continued ballistic missile and nuclear tests also have the stated purpose of targeting the United States.

But while the U.S. does stockpile weapons and forces in South Korea to potentially thwart or initiate an attack, the U.S. does not retaliate militarily.

Instead, U.S. armed forces merely stand ready as North Korea's nuclear and conventional weapons hold major U.S.-allied cities like Seoul and Tokyo at risk.

More from Business Insider: