Updated

New satellite imagery appears to show preparations beginning for a long-range rocket launch in North Korea despite international objections.

The image from a privately operated satellite was taken Wednesday at the Tongchang-ri site where North Korea says it plans to launch the rocket between April 12 and 16.

An analysis conducted for the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies says the image shows trucks and fuel tanks outside two large buildings that would be used to store propellant for the rocket. It also shows work under way at a gantry tower next to a mobile launch pad, with a crane being used to load equipment. The rocket itself is not yet visible.

"The image shows not only that the launch is going ahead but the preparations seem to be on schedule for the planned launch dates," said Joel Wit, visiting fellow at the institute and editor of its website on North Korea, "38 North."

North Korea says the launch is to fire an observation satellite into orbit and mark the centennial of the birth of the nation's founder, Kim il Sung. The U.S. says it is a cover to test long-range missile technology and violates U.N. Security Council resolutions.

President Barack Obama has appealed to the North Korean leadership to abandon the rocket plan but was promptly rebuffed by the North.

If the launch does go ahead, it will terminate a Feb. 29 accord between the longtime adversaries, under which the North agreed to nuclear concessions and a moratorium on long-range missile and nuclear tests in exchange for food aid.

The U.S. says the plans to provide the food to the impoverished communist nation are already on hold.

On Sunday, South Korean defense officials said the main body of the three-stage rocket was transported to a building in Tongchang-ri, which lies on North Korea's northwestern coast, about 35 miles (56 kilometers) from the northern border with China.

The institute's analysis suggests that the separate stages of the rocket will be moved from this building and assembled at the launch site which lies about 1,000 yards (meters) away. It predicted the first stage of the rocket will probably be moved to the launch pad in the next couple of days.

The image appears to show various other activities at the site, including a crew cutting brush away from the launch pad, to prevent it catching fire when the Unha-3 rocket takes off and burning its way to the adjacent buildings used to store the propellant.

Analysts describe Tongchang-ri as a more sophisticated launch site than used for previous North Korean rocket launches, allowing a southward flight path that would avoid sending it over other countries.

However, U.S. Assistant Secretary of Defense for Asia-Pacific Security Affairs, Peter Lavoy, said Wednesday the U.S. lacks confidence about the rocket's stability and that debris from it could cause casualties. He said the rocket is probably intended to land somewhere close to the Philippines or maybe Indonesia, but South Korea and the Japanese island of Okinawa could also be affected.

Philippine President Benigno Aquino III, a close U.S. ally, said Thursday he is gravely concerned that debris may fall on Philippine territory. He called the planned launch a "needless provocation" and urged North Korea to abandon it.

Crucially, for Washington, the latest test could demonstrate if North Korea is closer to perfecting a multi-stage rocket that could hit the United States.

North Korea also conducted long-range rocket tests in 1998, 2006 and 2009, but with limited success. North Korea has also conducted two nuclear tests. It is not believed to have mastered how to fit a nuclear weapon onto a missile.

The announcement of the latest launch came just two weeks after the Feb. 29 U.S.-North Korean agreement, which had buoyed hopes for improved relations between the wartime enemies under its new and untested leader, Kim Jong Un. He came to power after his father Kim Jong Il who died of a heart attack in December, taking Pyongyang's secretive, hereditary regime into a third generation.