The US defense officials confirmed that North Korea conducted another ballistic missile engine test on Friday. The officials said the latest engine trial is the third such test in recent weeks using similar technology.
Another official said that the initial assessment indicates that the engine technology could possibly be used in an eventual intercontinental ballistic missile.
The biggest fear of the US is that possession of an intercontinental ballistic missile could allow North Korea to threaten the continental United States. ICBM technology is considered difficult to develop, with advanced rocket design being a necessary step.