North Korea has said it plans to launch a satellite next month as part of its space program. South Korea considers the launch an attempt to develop a nuclear-armed missile.
Preparations for an apparent test launch were reported Monday, hours after U.S. President Barack Obama, in Seoul for a nuclear summit, warned of repercussions against any pursuit of nuclear weapons by the North.
"Here in Korea, I want to speak directly to the leadership in Pyongyang. The United States has no hostile intent toward your country," Obama said in a speech at Hankuk University of Foreign Studies in Seoul. "But by now it should be clear, your provocations and pursuit of nuclear weapons have not achieved the security you seek. They have undermined it."
A defense ministry official told CNN the North moved the rocket to a launch pad near the Chinese border.
The North Korean government has said any critical statement of its nuclear program would be seen as "a declaration of war."
The use of ballistic missile technology would violate a U.N. Security Council Resolution, as well as a deal for food aid from the United States.
"There will be no rewards for provocations. Those days are over," Obama said in his speech. "To the leaders of Pyongyang I say: This is the choice before you."
Obama warned North Korea would lose its promised food aid and face sanctions if it the long-range rocket is launched.