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Obama tells US troops at Korean DMZ: 'You guys are at freedom's frontier'

SEOUL -- President Barack Obama was greeted with cheers from U.S. troops as he visited the dining hall at Camp Bonifas at the start of his tour of the Demilitarized Zone on the Korean peninsula and told them that they were protecting "freedom's frontier."

Obama talked about how proud he was of the troops and joked about the NCAA basketball tournament. While, the president has visited the Republic of Korea twice before, this was his first time observing the 38th parallel and members of North Korea’s military.

At Camp Bonifas, Obama told U.S. troops that they are part of a "long line" of soldiers who have enabled South Korea to prosper. "You guys are at freedom's frontier," he said.

While at the DMZ, the president spoke to South Korean troops, then went to Observation Post Ouellette, the closest post overlooking the demarcation line on the most heavily guarded border in the world.

The observation post is about 25 miles northwest of Seoul inside the DMZ and just 100 yards from demarcation line. The North Korean army is visible from this observation post and it was expected that the North Koreans would jam cell phone signals while the president was visiting the area.

In advance of the trip, White House Deputy National Security Adviser Ben Rhodes said that the president’s visit to the DMZ “sends a clear message that the United States is committed to the security of our ally and that the commander in chief stands with those 28,000 Americans that are serving on the Korean peninsula.”

The United States has more than 28,000 troops in South Korea, a legacy of the Korean War six decades ago. Camp Bonifas was renamed in 1986 in honor of US Army Capt. Arthur Bonifas, who was killed by North Korean soldiers in a 1976 ax attack.

Every president since President Ronald Reagan has visited the DMZ. 

The president’s visit comes a day before he is set to participate in the second international Nuclear Security Summit.

While the subject of North Korea is not officially on the list of topics for the summit, the North's presence looms large because of the announcement that it is planning to test a long-range rocket in April.

There were some indications that North Korea was going to suspend some of its nuclear activities. But then the North Koreans announced a satellite launch in April that, according to Rhodes, “can also serve, frankly, as a ballistic missile test as well.” Obama is expected to call upon Chinese President Hu Jintao to urge North Korea to back away from the planned launch.

NBC News' Shawna Thomas reported from Seoul, South Korea. NBC News' Alicia Jennings and Kristen Welker reported from Camp Bonifas.

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