We start with a basic premise stated by Washington, namely that the United States will prevent the DPRK from developing a missile (ICBM) capable of reaching American territory with a nuclear warhead. The DPRK is in response developing an ICBM that can reach US soil in order to gain the ultimate deterrent weapon and so ensure its safety. In reality, we cannot know what the DPRK’s capabilities are until they test them.
Source