When South Korean President Moon Jae-in arrived this week at Seoul's largest weapons expo ever in the back seat of a fighter jet, he didn't present the image of a leader bent on making peace with North Korea.

Under Moon, South Korea has not only continued many of the military programs approved under his conservative predecessors, but pushed already large defense budgets to new highs, negotiated an end to U.S. restrictions on its missile program, and announced plans for the nation's first aircraft carrier, among a plethora of other advanced weapons.

Whatever the outcome of Moon's last-ditch efforts to a achieve a breakthrough with North Korea before he leaves office in May, that military buildup appears a lasting legacy.