It is the Trump administration's latest move in the increasingly escalating fight against drug cartels in South America.
"We are now formally classifying fentanyl as a weapon of mass destruction," Trump said when he signed the presidential order.
"No bomb does what this does – 200,000-300,000 people die every year, as we know," Trump continued.
Fentanyl is a so-called synthetic opioid, which can be many times more potent than heroin.
In recent months, the United States has carried out deadly attacks on ships allegedly transporting drugs off the coast of mainly Venezuela, but also Colombia.
