U.S. Vice President Mike Pence stared across the demilitarized border between North and South Korea on Monday, a day after North Korea’s failed missile launch, reiterating that the U.S. “era of strategic patience” with Pyongyang was over.

Pence is on the first stop of a four-nation Asia tour intended to show America’s allies, and remind its adversaries, that the Trump administration is not turning its back on the increasingly volatile region.

The demilitarized zone (DMZ) is a heavily mined, four-km-wide (2.5-mile-wide) strip of land lined with barbed wire running across the Korean peninsula, with soldiers on both sides in a continual eyeball-to-eyeball standoff.

Pence, whose father served in the 1950-53 Korean War, said the United States would stand by its “iron-clad alliance” with South Korea and was seeking peace through strength.