North Korea announced plans to deploy an Earth observation satellite into orbit in April. The announcement followed a pledge by Pyongyang to halt missile and nuclear activity in exchange for food assistance from the United States.
"South Korean and U.S. military authorities understand that North Korea has moved the main body of a long-range missile to Dongchang-ri in preparation for launch," a South Korean military official told the Yonhap news agency on condition of anonymity.
The announcement came as world leaders arrived in Seoul for a Nuclear Security Summit. Obama said during a news conference with Russian President Dmitry Medvedev that Pyongyang should call off the scheduled launch.
"(W)ith respect to North Korea, we are going to be both sending messages to North Korea that they should not go forward with this missile launch, which would violate existing U.N. Security Council resolutions," Obama said. "And our hope is, is that we can resolve these issues diplomatically."
South Korean Prime Minister Kim Hwang-sik had called for a heightened state of alert ahead of the planned mid-April launch.