New Delhi, Dec. 16 -- US President Donald Trump on Monday signed an executive order formally designating fentanyl as a "weapon of mass destruction", classifying the synthetic opioid not only as a lethal narcotic but as a substance that could be treated as a potential chemical weapon under US law.

In a White House press release accompanying the order, the president underscored the drug's lethality and the scale of the public health crisis it has caused. "Illicit fentanyl is closer to a chemical weapon than a narcotic. Two milligrams, an almost undetectable trace amount equivalent to 10 to 15 grains of table salt, constitutes a lethal dose. Hundreds of thousands of Americans have died from fentanyl overdoses", the statement said.

The exec...