North Korea has launched a rocket into space Sunday in defiance of international condemnation. Japan, South Korea and the U.S. State Department have confirmed the launch.

The payload of the rocket remains unclear. North Korea has said the rocket was to carry a satellite into space, but the United States, South Korea and other nations fear it could be a missile with a warhead attached.

North Korea carried out the launch despite calls from the U.S., Japan and others to refrain from a launch they say is banned under a U.N. Security Council resolution barring the North from ballistic missile activity.

Preparations for sending “an experimental communications satellite” into space were complete, North Korea’s state-run media had reported Saturday, announcing: “The satellite will be launched soon.”

Leaders from the five nations negotiating to disarm the North have tried in the past few weeks to stop the launch. The U.S., South Korea, Japan and others suspect the launch is a guise for testing the regime’s long-range missile technology — a step toward eventually mounting a nuclear weapon on a missile capable of reaching Alaska and beyond.