When North Korea launched long-range missiles this summer, and again on Friday, demonstrating its ability to strike Guam and perhaps the U.S. mainland, it powered the weapons with a rare, potent rocket fuel that U.S. intelligence agencies believe initially came from China and Russia.
"A Potent Fuel Flows to North Korea. It May Be Too Late to Halt It." is from the September 17, 2017 World section of The New York Times. It was written by William J. Broad and David E. Sanger and narrated by Kristi Burns.