One of the Trump administration’s proudest first-year accomplishments in the struggle against opioid use is being quietly undone with a resurgence in deep web drug sales.

Right now, anyone with $500 can buy enough fentanyl to kill 100 people. More than a dozen dealers are selling the potent synthetic opioid and its analogues — which killed 20,000 Americans in 2016 — on darknet markets accessible with the Tor anonymous browser.