North Korea has probably developed long-range missiles that could hit the United States, according to the South Korean defence ministry.
They came to the conclusion after analysing parts of a North Korean rocket that was launched earlier this month.
The South Korean navy retrieved the first stage of the rocket that fell into the sea off its west coast.
Scientists estimate it has the capacity to fire a half tonne payload 10,000 kilometres.
There have been long-held suspicions in the west that North Korea had this type of technology.
The UN has banned North Korea from testing missile or nuclear technology after nuclear weapons tests in 2006 and 2009.
The UN Security Council condemned the launch on Dec 12, 2012, though North Korea said the mission was simply to put a weather satellite in orbit.
Experts say the north is still years away from making a nuclear device small enough to mount on a missile, and they say there is no evidence that North Korea had perfected the technology to protect a warhead from re-entry into the earth’s atmosphere.
In Pyongyang, state media reported that North Korean leader Kim Jong-un wanted to develop rockets with ever bigger carrying capacity.