NEW YORK — When North Korea launched long-range missiles this summer, and again on Friday, demonstrating its ability to strike Guam and perhaps the US mainland, it powered the weapons with a rare, potent rocket fuel that US intelligence agencies believe initially came from China and Russia.
The US government is scrambling to determine whether those two countries are still providing the ingredients for the highly volatile fuel and, if so, whether North Korea’s supply can be interrupted. Among those who study the issue, there is a growing belief that the United States should focus on the fuel, either to halt it, if possible, or to take advantage of its volatile properties to slow the North’s program.
But it may well be too late. Intelligence officials believe that the North’s program has advanced to the point where it is no longer as reliant on outside suppliers, and that it may itself be making the deadly fuel, known as UDMH. Despite a long record of intelligence warnings that the North was acquiring both forceful missile engines and the fuel to power them, there is no evidence that Washington has ever moved with urgency to cut off Pyongyang’s access to the rare propellant.
Classified memos from both the George W. Bush and Obama administrations laid out how the North’s pursuit of the highly potent fuel would enable it to develop missiles that could strike almost anywhere in the continental United States.
In response to inquiries from The New York Times, Timothy Barrett, a spokesman for the director of national intelligence, said that “based on North Korea’s demonstrated science and technological capabilities — coupled with the priority Pyongyang places on missile programs — North Korea probably is capable of producing UDMH domestically.” UDMH is short for unsymmetrical dimethyl hydrazine.
The White House and US intelligence agencies declined to answer questions about what, if anything, they were doing to cut off North Korea’s supplies.
But in interviews with four senior US officials who served as the North advanced its program, none could recall any specific discussion of how to disrupt North Korea’s access to the one fuel that now powers its long-range missiles.