The North Korean missile that soared high above the Sea of Japan early Monday was hailed by state-run television as a "shining success." But to US officials, it was a most unwelcome surprise: a weapon with intercontinental range, delivered years before most Western experts believed such a feat possible.

Hours after the apparently successful test, intelligence agencies continued to run calculations to determine precisely how the missile, dubbed the Hwasong-14, performed in its maiden flight. But the consensus among missiles experts was that North Korea had achieved a long-sought milestone, demonstrating a capability of striking targets thousands of miles from its coast.