Specifically, in a blockbuster report this morning, the NYT alleges that North Korea has been making black-market purchases of powerful rocket engines from a Ukrainian factory citing "expert analysis being published Monday and classified assessments by American intelligence agencies."

The studies may solve the mystery of how North Korea began succeeding so suddenly after a string of fiery missile failures, some of which may have been caused by American sabotage of its supply chains and cyberattacks on its launches. After those failures, the North changed designs and suppliers in the past two years, according to a new study by Michael Elleman, a missile expert at the International Institute for Strategic Studies.

According to the report, analysts who studied photographs of Kim Jong-un, inspecting the new rocket motors concluded that they derive from designs that once powered the Soviet Union’s missile fleet. "The engines were so powerful that a single missile could hurl 10 thermonuclear warheads between continents."

On June 1, Mr Elleman struck an apprehensive note. He argued that the potent engine clearly hailed from “a different manufacturer than all the other engines that we’ve seen.” Mr Elleman said the North’s diversification into a new line of missile engines was important because it undermined the West’s assumptions about the nation’s missile prowess: “We could be in for surprises.” That is exactly what happened. The first of the North’s two tests in July of a new missile, the Hwasong-14, went a distance sufficient to threaten Alaska, surprising the intelligence community. The second went far enough to reach the West Coast, and perhaps Denver or Chicago.