A British man could face life in jail after pleading guilty to conspiring to import 100 kilos of North Korean-produced methamphetamine into the United States.
Scott Stammers, 46, will be subject to a mandatory 10-year term, US authorities said.
He was arrested along with four co-defendants, following a lengthy investigation by the Drug Enforcement Administration (DEA), said Preet Bharara, the United States attorney for the southern district of New York.
Mr Bharara said: "Scott Stammers conspired to import into the United States 100 kilograms of dangerously pure North Korean methamphetamine.
"Thanks to the work of the DEA and the co-operation of law enforcement partners around the world, including in Thailand, Liberia and Romania, Stammers' scheme ended, not with the North Korean methamphetamine flooding American streets as he had intended, but rather with a guilty plea in a Manhattan federal court."
A total of five defendants were arrested in Thailand in September 2013 on suspicion of preparing to ship the drugs, which were more than 99% pure, by boat.
Three of the other defendants pleaded guilty earlier this month. The fifth is scheduled to go on trial in New York in September.
Mr Bharara said: "Stammers faces a maximum possible term of life in prison and a mandatory term of 10 years in prison. Any sentence will be determined by the judge. A sentencing date has not been scheduled."
Mr Bharara has previously said that the remaining defendant, Philip Shackels, 32, is also British.
His trial is scheduled to begin on September 21.