N. Korea building missile launch pad capable of aiming at U.S.: report

A satellite image of the Sohae site taken in Oct. 2013 and released by the U.S.-Korea Institute at Johns Hopkins on Wednesday.

North Korea is improving one of its missile launch sites and may soon be able to fire rockets large enough to hit mainland United States, according to experts.

Recent satellite images appear to show that one of the country's launch stations has been modified to accommodate an intercontinental missile 25 percent larger than one it fired into space in Dec. 2012, according to a report by Johns Hopkins University’s U.S.-Korea Institute (USKI) published Wednesday.

The report added that the launch pad, which could be ready as early as March, would allow for "a more robust rocket test program in the future involving larger space launch vehicles and road-mobile ballistic missiles able to attack targets in Northeast Asia and the United States."

Director of National Intelligence James Clapper warned the Senate Intelligence Committee on Wednesday LINK? that North Korea had gone through with its threat to continue its nuclear weapons program, posing “a serious threat to the United States and to the security environment in East Asia.”

The satellite images appeared to show that North Korea has also tested a rocket engine for a new road-mobile intercontinental missile called the KN-08, the report said. Rockets have been displayed at parades in the capital Pyongyang but analysts have speculated these were mock-ups.

Outwardly, however, North Korea is on something of a charm offensive, having hosted the press in New York, London and Beijing in the past week.

North Korea's ambassador to the U.K., Hyun Hak-bong, gave an interview to Sky News on Thursday in which he blamed the U.S. for its hostile policies. He said his country had "no option but to have the nuclear deterrent."

The North sent the South an open letter earlier this month in which it called for an end to hostilities. The letter warned that the tense stand-off between the two nations could lead to "an all-out…nuclear war" from which "no Korean can escape."

It comes ahead of the annual joint military exercises between the U.S. and South Korea. Last year more than 10,000 American personnel participated. North Korean leader Kim Jong Un responded with a series of internationally-condemned missile tests and suggested he was about to launch a nuclear attack.