Most analysts do not believe that North Korea has a missile powerful enough to deliver a nuclear warhead to the United States mainland or that it is reckless enough to strike the American military in the Pacific. Still, with the North’s bellicose language showing no signs of letting up, the United States said Wednesday that it was speeding the deployment of an advanced missile defense system to Guam in the next few weeks, two years ahead of schedule, in what the Pentagon said was a “precautionary move” to protect American naval and air forces from the threat of a North Korean missile attack.

Testifying before a parliamentary hearing, Defense Minister Kim Kwan-jin of South Korea said the missile North Korea had moved to the east coast, possibly “for demonstration or for training,” appeared not to be a KN-08, which analysts say is the closest thing North Korea has to an intercontinental ballistic missile, though its exact range is not known. The new missile was unveiled during a military parade in the North Korean capital, Pyongyang, in April last year.

South Korean news media quoted military officials as saying that the missile was a Musudan. Deployed around 2007, the Musudan is a ballistic missile with a range of more than 1,900 miles, according to the South Korean Defense Ministry. Guam is nearly 2,200 miles from North Korea.

Wee Yong-sub, an army colonel and deputy spokesman for the Defense Ministry, would say only that the South Korean and American militaries had been closely monitoring the movements of all North Korean missiles, including the Musudan.