“First of all, with regards to any provocations from the North, I think it's very clear that South Korea and the United States have a strong cooperative relationship and that, when those provocations occur, that we will work together to determine what kind of response should be provided if necessary,” Panetta said after a meeting with his South Korean counterpart Kim Kwan Jin.

The top US defense official said he already agreed with his colleague that both the United States and South Korea will be watching closely after the developments in North Korea.

“With regards to future missile defense, that's an area that we continue to discuss in order to make sure that we have all of the defenses necessary to deal with the missile threat coming from North Korea, and whatever steps are necessary to try to make sure that we're prepared for that,” he said.

“We just deployed, or we just talked about deploying a TPY-2 radar system to Japan specifically in order to protect against that kind of missile threat, and we will continue to work with our friends in the region to further develop that kind of capability,” Panetta added.

Earlier in the month the North Korean military said that the US mainland was within the strike range of its strategic missile forces.

In October 2006, North Korea became the world’s eighth nuclear power, conducting an underground nuclear weapons test.

Although the country’s nuclear program and its development of long-range missile systems has been condemned by the international community, Pyongyang has vowed to continue its controversial missile development program.

North Korea has already deployed a number of domestically-built missiles, including some capable of hitting the American territory of Guam in the Pacific, in addition to South Korea and Japan.