South Korea’s defence ministry say a satellite sent into space by North Korea is in orbit but it is not yet clear whether it is working.
North said it is a communications satellite and that Sunday’s launch was a complete success.
The move was internationally condemned as North Korea is banned under UN sanctions from using any ballistic missile technology.
The UN has vowed to impose further sanctions as punishment.
The US said on Monday that this could include a range of economic sanctions that would further isolate North Korea and send a clear signal that the resolve of the international community is firm.
The US has also said it will help South Korea deploy an advanced missile defence system as soon as possible.
The South’s defence ministry said the launch indicated the North now has long-range missiles.
But it remains unclear whether it has developed the technology to make a missile re-enter the atmosphere, critical if it is to use the missile as weapon.
The North insists its space programme is purely scientific in nature but the US, South Korea and even Pyongyang’s ally China say the rocket launches are aimed at developing inter-continental ballistic missiles.
Last month North Korea also carried out its fourth test of a nuclear bomb.