U.S. President Barack Obama visited the heavily armed border with North Korea on Sunday morning amid reports that the North moved a rocket it says will carry a satellite to a launch pad for imminent liftoff. Obama told troops there that they are at "freedom's frontier." U.S. President Barack Obama looks through binoculars at North Korea from Observation Post Ouellette in the Demilitarized Zone on Sunday. /AP-Newsis At a press conference afterwards, Obama said a look at the North Korean side of the border through binoculars from the demilitarized zone is "like you're looking across 50 years into a country that has missed 40 years or 50 years of progress." Obama is the fourth U.S. president to visit the DMZ after Ronald Reagan (1983), Bill Clinton (1993), and George W. Bush (2002).