Donald Trump has announced he will pursue a change in the law to allow "big drug pushers" to face the death penalty.
Under current US law only murder is a capital crime but Mr Trump said: "We have to change the laws. The Department of Justice is working very hard on that.
"This isn’t about nice anymore. Toughness is the thing they (drug dealers) most fear. That toughness includes the death penalty."
The US president said there should be "zero tolerance" and he could not personally understand why anyone would be opposed to executing dealers who "kill thousands of people over their lifetime".
He said: "Together we will end the scourge of drug addiction once and for all. We will do whatever we have to do but we’re going to win."
Mr Trump added: "We’ll build the wall to keep the damn drugs out."
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The president was announcing his long-awaited plan to combat America’s opioid crisis in a speech in New Hampshire, one of the worst affected states.
He said Congress would spend $6 billion (£4.3bn) tackling it next year, and he was considering having the US Government sue big drug companies who manufacture potent opioids.
TV adverts will also be launched to "scare" young people away from abusing drugs, he added.
Mr Trump said "great commercials" would run during the "right shows" in the manner of anti-smoking campaigns.
The president also announced a new website called crisisnextdoor.gov which would warn of the dangers of opioids like fentanyl.
He added: "We will raise a drug-free generation of American children. Addiction is not our future.
The White House will also ask Congress to lower the amount of drugs an offender needs to possess to make them eligible for certain minimum jail sentences.
In addition, the plan aims to reduce by one third the amount of opioid prescriptions made by doctors over the next three years.
The Justice Department will pursue negligent doctors and pharmacies with criminal and civil action.
Mr Trump’s plan also includes more help for addicts, expanding access to treatment facilities.
According to the Centres for Disease Control and Prevention, 42,000 people died from opioid overdoses in the US in 2016, many of them from the street drug fentanyl which has flooded states including New Hampshire.
Mr Trump chose New Hampshire for the launch amid speculation he could face a 2020 primary challenge from a fellow Republican.
New Hampshire will be the first state primary when the Republican Party selects its nominee, and Mr Trump has suffered falling poll ratings there.
Two possible challengers, Senator Jeff Flake and Ohio Governor John Kasich, have been making visits to the state.
Last week Mr Flake, speaking in New Hampshire, publicly accused Mr Trump of presiding over a "degradation of the United States and her values".
No sitting US president has faced a primary contest since George H. W Bush was taken on by fellow Republican Pat Buchanan in 1992.
Fergus Cullen, a former chairman of the New Hampshire Republican State Committee, told The Telegraph he believed it was "inevitable" Mr Trump would face a 2020 primary challenge.
He said: "The question is whether it’s one or is it many? History tells you that any president who faces a serious challenge might win the primary, but they don’t end up winning the general election."