North Korea launched a long-range rocket carrying what it called a satellite, drawing renewed international condemnation just weeks after it carried out a nuclear bomb test.
Critics of the rocket program say it is being used to test technology for a long-range missile.
South Korea and the United States said they would explore whether to deploy an advanced missile defense system in South Korea "at the earliest possible date."
The US Strategic Command said it had detected a missile entering space, and South Korea's military said the rocket had put an object into orbit.
North Korea said the launch of the satellite Kwangmyongsong-4, named after late leader Kim Jong Il, was a "complete success" and it was making a polar orbit of Earth every 94 minutes. The launch order was given by his son, leader Kim Jong Un, who is believed to be 33 years old.
North Korea's state news agency carried a still picture of a white rocket, which closely resembled a previously launched rocket, lifting off. Another showed Kim surrounded by cheering military officials at what appeared to be a command center.
Isolated North Korea's last long-range rocket launch, in 2012, put what it called a communications satellite into orbit, but no signal has ever been detected from it.