WASHINGTON, Dec 15 (Reuters) - President Donald Trump signed an executive order on Monday declaring fentanyl a weapon of mass destruction, a move that dramatically expands the U.S. government’s authority to fight the synthetic opioid blamed for tens of thousands of American overdose deaths each year.

The designation, unprecedented for a narcotic, signals Trump’s intent to treat fentanyl not merely as a public health crisis but as a national security threat on a par with chemical warfare.