“If North Korea does not have UDMH, it cannot threaten the United States, it’s as simple as that,” said Senator Edward J. Markey, Democrat of Massachusetts, who sits on the Senate Foreign Relations Committee. “These are the issues that the U.S. intelligence community has to answer: from which countries they receive the fuel — it’s probably China — and whether North Korea has a stockpile and how big it is.”

Today, the chemical is made primarily by China, a few European nations and Russia, which calls it the devil’s venom.