North Korea said on Wednesday it was injecting fuel into a long-range rocket “as we speak” ahead of a launch condemned by its neighbors and the West.
The launch is set to take place between Thursday and next Monday and has prompted neighbors such as the Philippines to re-route their air traffic just in case.
Japan said it would shoot down the rocket if it crossed its airspace.
The launch of the Unha-3 rocket, which North Korea says will merely put a weather satellite into space, breaches U.N. sanctions imposed to prevent Pyongyang from developing a missile that could carry a nuclear warhead.
“This launch will give credence to the view that North Korean leaders see improved relations with the outside world as a threat to their system,” Clinton told cadets at the U.S. Naval Academy in Annapolis, Maryland.
“And recent history strongly suggests that additional provocations may follow.”
She also called on China to do more to ensure regional stability.
China, impoverished North Korea’s only major ally, on Tuesday reiterated its pleas for calm and said it had “repeatedly expressed its concern and anxiety about the developments”, Foreign Ministry spokesman Liu Weimin told a press briefing in Beijing.