LAURA SULLIVAN, HOST:
President Obama is in South Korea to take part in a nuclear security summit with 52 other heads of state in the South Korean capital, Seoul. Earlier today, the president met with some of the 28,000 U.S. troops in the country, and he paid a visit to the military armistice line that has divided North and South Korea for six decades now.
There have been high hopes that the recent change in leadership in North Korea might lead to improved relations, but tensions are rising again. North Korea has a planned missile launch scheduled for April. Reporter Doualy Xaykaothao visited the demilitarized zone to see if anything has changed since North Korean leader Kim Jong Un took power three months ago.
DOUALY XAYKAOTHAO, BYLINE: Cold winds blow through pine trees and across nearby mountains. In the horizon are guard posts and cameras. There's little movement, except for wildlife. Lieutenant Colonel Ed Taylor lives and works on the armistice line and sleeps in a bed right next to North Korea.
LT. COL. EDWARD TAYLOR: I cannot compare it to anything I've ever done. And I say that with 23 years in the Army and two deployments to Iraq.
XAYKAOTHAO: He commands the only combined U.S. and South Korean battalion on the Korean Peninsula. Twenty-four hours a day, 365 days a year, the joint forces watch, anticipate and train for possible North Korean infiltration, unusual movements by the North Korean People's Army or defections. His troops are the South's trip wire, the first of some 28,000 U.S. soldiers to face North Korea's forces if they ever crossed over.
TAYLOR: When you are actually standing on what is the de facto border - it's not an official border, it's a military demarcation line - and there is nothing between you - no fence, no barrier - and you are standing essentially on a line that's drawn on the ground, and you're looking across at a North Korean soldier who is fulfilling the same duty and standing there looking back across at you, it's a little surreal.
XAYKAOTHAO: Surreal, not just for him, but also for more than 600,000 tourists who are allowed to visit parts of the DMZ annually. Colonel Taylor, who is always armed and wearing a bulletproof vest when he's near the demarcation line, says the responsibility of the UNC Security Battalion also includes protecting visitors, to ensure they don't provoke the North Korean guards. But he's also witnessed the opposite.
TAYLOR: From the North Korean soldiers, they do engage sometimes in immature behavior, you know, throat slashing gestures. They will open up their holsters, flip their holster open very quickly, to give the impression that they might be thinking about drawing their weapon.
XAYKAOTHAO: He says his soldiers, all of whom are handpicked to work on the front line, behave more professionally. New Zealander Lieutenant Ewan Sinclair from the Military Armistice Commission says the DMZ is the only communications link between the U.N. Command and the North Korean People's Army.
LT. EWAN SINCLAIR: One of the ways we do that is maintaining a single fine line that runs from our office here just north to Pyongyang gap.
XAYKAOTHAO: And when the North doesn't want to take the call, the lieutenant says, in the interest of transparency, they have to step outside and use a bullhorn. That was the case when he tried to deliver a message about South Korea's live fire exercises in the Yellow Sea.
SINCLAIR: And on these occasions, the Korean People's Army, because they don't want to recognize in principal, the fact that the Republic of Korea has any right to conduct live fire exercises in the Yellow Sea, they refused to receive the message over phone line.
XAYKAOTHAO: So the bullhorn came out, and Lieutenant Sinclair shouted the news across the demarcation line.
SINCLAIR: Just conducting business as usual, moves at the rate of a glacier. It's so slow that anytime we try and get business done, it can take upwards of two weeks just for a simple task.
XAYKAOTHAO: But that's how life works at the most heavily guarded border in the world. North Korea's new leader may be consolidating his power in Pyongyang, but along the armistice line, little has changed in the last 59 years. The 1,300 temporary markers that divide the Korean Peninsula remain as they were, only rusted now. For NPR News, I'm Doualy Xaykaothao at the Korean demilitarized zone in South Korea.