Before the launch, North Korea had said it would put a satellite into orbit, but the launch is viewed by others as a front for a ballistic missile test.
The move will test already shaky regional security. South Korea had condemned the planned launch as a "direct challenge against the international community," and had warned that North Korea would pay a "grave price" if it went ahead.
Japan's Prime Minister Shinzo Abe also had urged North Korea to "refrain" from the launch and said his cabinet was working closely with the United States and South Korea to gather information.
Chinese Foreign Ministry spokesman Lu Kang had expressed "deep concern" in advance of the launch.
"We hope (North Korea) will exercise restraint and caution in its actions. It should not act in a way that may escalate tensions on the peninsula," Lu said Wednesday.
Japanese and South Korean airlines have altered flight paths to avoid possible falling rocket parts
. Based on coordinates provided by North Korea to the International Maritime Organization, the first stage and nose cone of the rocket will drop off in waters between South Korea and China. Its second stage is expected to fall into waters off the Philippines' northern coast.
Satellite... or nuclear missile?
At present, North Korea is believed to have one satellite in orbit
, the Kwangmyongsong 3-2, though doubts have been raised about whether it is functioning.
While Pyongyang claims that its space program is entirely peaceful, many international observers think the true purpose is military.
The same technology used to launch a satellite into orbit could potentially deliver a nuclear warhead.
China, the Soviet Union and the United States have all used intercontinental ballistic missiles to launch satellites in the past.
The Unha rocket used to launch North Korea's last satellite is believed to be based upon the Taepodong long-range ballistic missile, which has an estimated range of around 5,600 miles
That would put Australia, much of Western Europe, and the U.S. West Coast in range of a North Korean warhead.
According to multiple experts, North Korea has at least a dozen and perhaps as many as 100 nuclear weapons
, though at present it lacks sophisticated delivery mechanisms.
North Korea claimed
to have tested a hydrogen bomb in early January.
According to a 2015 report
on Pyongyang's space program by 38 North, testing rockets through satellite launches would provide invaluable data for potential future ICBMs.
"Even failed satellite launches would be a learning experience," wrote aerospace engineer John Schilling.
Schilling said a key sign to look out for in future North Korean satellite launches would be attempts to test an advanced re-entry vehicle, vital for an effective ICBM.