Heino Klinck, the deputy assistant secretary of defense for East Asia, made the remarks at a forum hosted by the Korea-U.S. Alliance Foundation and the Heritage Foundation in Washington.

A senior Pentagon official on Wednesday said the U.S. has never taken the military option off the table when dealing with North Korea.

He alluded to U.S. President Donald Trump’s remarking earlier this week, "Hopefully, we don't have to use [military force against North Korea], but if we do, we'll use it. If we have to, we'll do it."

Klinck pointed out that a joint South Korea-U.S. aerial drill originally scheduled for December has not been canceled but only postponed and quoted U.S. Defense Secretary Mark Esper as urging the North not to misunderstand such an "act of goodwill" and a "good-faith effort" as weakness.

"The military exists to serve as a deterrent. It serves as a stabilizing force," Klinck said. "If deterrence fails, it is its role to fight and win."

"We, the Department of Defense, have provided the space and intentionally so, for the diplomats of the State Department to do their work," he added. "We have shown restraint by not responding to every single North Korean provocation, whether it was a rhetorical provocation, or something like a missile test."

But "there may come a time where our response may be different, and where the lead for the State Department may switch to something else," he said. "It's our role within the Department of Defense to give our civilian leaders options."