North Korea launched a long-range rocket on Wednesday, in defiance of UN sanctions threats over what Pyongyang's critics insist is a disguised ballistic missile test.
"It (the rocket) has been launched," a South Korean defense ministry spokesman said without elaborating further.
The Yonhap news agency, citing a government source, said the rocket had taken off from the Sohae satellite launch center at 9:51 am and was immediately detected by navy vessels deployed by Seoul in the Yellow Sea.
There was no immediate report on the success of the launch, but the Japanese government said the missile had passed its southern island chain of Okinawa around 12 minutes after take-off.
"The missile that North Korea calls a satellite passed over Okinawa around 10:01 (am). We launched no interception," it said.
Japan had deployed missile defense systems to intercept and destroy the rocket if it looked set to fall on its territory.
The United States had also deployed ships from its Pacific fleet equipped with ballistic missile defenses.