NEW YORK (Reuters) - A U.S. digital currency specialist living in Singapore has been arrested and criminally charged with helping North Korea use cryptocurrency and blockchain technology to evade American sanctions, the U.S. Department of Justice said on Friday.

Federal prosecutors in Manhattan said Virgil Griffith, 36, traveled to North Korea via China in April to attend the Pyongyang Blockchain and Cryptocurrency Conference, despite being denied permission by the U.S. Department of State to go.

Griffith, who has a doctorate from the California Institute of Technology, gave a presentation on topics preapproved by North Korean officials, provided valuable technical information, and engaged in talks about using cryptocurrency technology to circumvent sanctions and launder money, prosecutors said.

A lawyer for Griffith did not immediately respond on Friday to requests for comment.

Griffith was arrested on Thursday at Los Angeles International Airport, and charged with conspiring to violate the International Emergency Economic Powers Act, which carries a maximum 20-year prison term.

Prosecutors said Griffith was expected to appear on Friday in Los Angeles federal court.

His case was announced one day after North Korea launched two short-range rockets off its eastern cost, ahead of a year-end deadline that Pyongyang had given the White House to show flexibility in stalled denuclearization talks.

“The consequences of North Korea obtaining funding, technology, and information to further its desire to build nuclear weapons put the world at risk,” FBI Assistant Director-in-Charge William Sweeney said in a statement.

“It’s even more egregious that a U.S. citizen allegedly chose to aid our adversary,” he added.

According to a criminal complaint, Griffith’s presentation titled “Blockchain and Peace” described how blockchain technology including a “smart contract” could help North Korea.

Prosecutors said Griffith later started work on making it easier to move cryptocurrency between North Korea and South Korea and encouraged other U.S. citizens to travel to North Korea, including for the same cryptocurrency conference in 2020.

The complaint said a search this month of Griffith’s cellphone with his consent uncovered an Aug. 6, 2019, message to an unnamed individual, known as Individual-2, indicating a need to send some cryptocurrency between North Korea and South Korea.

“Individual-2 asked, in sum and substance, ‘Isn’t that violating sanctions?’ Griffith replied, ‘it is,’” the complaint said.

The case is U.S. v. Griffith, U.S. District Court, Southern District of New York, No. 19-mag-10987.