An American professor was detained by officials as he was trying to leave North Korea from Pyongyang’s international airport on Saturday morning, according to ABC News. Tony Kim, 58, taught accounting at the Pyongyang University of Science and Technology for about a month. Kim was trying to leave with his wife on a flight to China, a university spokesman stated.

Tony Kim, who also goes by his Korean birth name, Kim Sang-duk, was detained in North Korea, according to Park Chan-mo, the chancellor of the Pyongyang University of Science and Technology, according to ABC News.

“He was prevented from getting on the flight out of Pyongyang… We don’t comment further than this.”

Pyongyang University of Science and Technology. Park said Kim taught accounting at the university for about a month. (AP Photo)

In North Korea, the Pyongyang University of Science and Technology is the only privately funded university. The institution opened its doors and began holding classes in 2010. It is unique in North Korea for having a large number of foreign staff members.

According to CNN, the detention of the U.S. citizen was confirmed by Martina Aberg, deputy chief of mission at the Embassy of Sweden in Pyongyang. The Swedish Embassy represents U.S. interests in North Korea as Washington and Pyongyang have no direct diplomatic relations.

Currently, there are at least two other U.S. citizens who are known to be in North Korean custody, bringing the total number of U.S. citizens detained in North Korea up to three.

The detained American is a professor with the frequently-used Korean surname “Kim,” according to South Korea’s Yonhap News Agency, Aberg told CNN.

US citizen has been detained in North Korea, according to Sweden, which represents US interests there in North Korea https://t.co/4Vve59Tf8e pic.twitter.com/MSMns55ucQ — CNN (@CNN) April 23, 2017

Otto Warmbier, 21, a student at the University of Virginia, was detained at Pyongyang airport on January 2 of 2016, after visiting the country with a tour group. After being found guilty of removing a political sign from a hotel wall, Warmbier has since been sentenced to 15 years of hard labor, according to Aljazeera.

Kim Dong Chul, a naturalized U.S. citizen of Korean origin, was arrested in October of 2015. North Korea sentenced him to 10 years of hard labor on espionage charges in 2016.

In regards to Kim, the State Department said it was aware of the report on an American citizen being detained, but would not talk further “due to privacy considerations.” There have been no further details released on why Kim was detained at the airport.

The detention of this U.S. citizen comes at a time of extremely heightened tensions between the U.S. and North Korea.

North Korea Threatens To Sink U.S. Carrier Aircraft

North Korea detaining a U.S. citizen comes at the heels of North Korea has just threatened to strike United States aircraft carrier, USS Carl Vinson, with one single strike. The newspaper likened the U.S. aircraft carrier to a “gross animal” and said a strike on the carrier would be “an actual example to show our military’s force.”

The aircraft carrier USS Carl Vinson [Image by Mass Communication Specialist 2nd Class Sean M. Castellano/U.S. Navy via Getty Images]

The United States has been silent on the location of the carrier strike group as it approaches the area. Mike Pence, U.S. Vice President, said on Saturday it would arrive “within days,” but gave no further details.

President Donald Trump ordered the USS Carl Vinson carrier strike group to sail to waters off the Korean peninsula, according to Reuters. This order was in response to rising tension over the North’s nuclear and missile tests, and its threats to attack the United States and its Asian allies.

North Korea Threatens To Sink US Aircraft Carrier With ‘A Single Strike’ https://t.co/rTDIMccTjH — Inquisitr News (@theinquisitr) April 23, 2017

Japan announced Sunday that two of its destroyers began conducting joint naval drills with a USS Carl Vinson aircraft carrier strike group in the western Pacific Ocean, according to CNN.

North Korea’s Unknown Nuclear Capabilities

North Korea has conducted five nuclear tests, two of them last year, and is working to develop nuclear-tipped missiles that can reach the United States, according to Reuters.

More recently, North Korea stunned the nation when state television aired chilling footage of the United States being hit by a nuclear bomb in a World War 3 simulation during their Day of the Sun festival.

#NorthKorea wipes out #US with nuclear strike in chilling simulation video during Day of the Sun festival https://t.co/M0uBBP2Txz pic.twitter.com/05CCvSc1g4 — KoreanPeninsulaNews (@KoreanWarNews) April 19, 2017

On April 15, many around the world watched as Pyongyang displayed their latest Intercontinental Ballistic Missiles (ICBMs) and submarine-based missiles during their 2017 military parade.

Pyongyang has poured an enormous amount of resources into developing its nuclear and missile arsenals.

On Thursday, after the North Korean state media warned the United States of a “super-mighty preemptive strike,” Trump then praised Chinese efforts to rein in “the menace of North Korea.”

North Korea Threatens Nuclear War With Australia, Alliance With US Is A ‘Suicidal Act’ https://t.co/Z7MfUzYvwV — Inquisitr News (@theinquisitr) April 23, 2017

North Korea maintains that their nuclear program was created for self-defense. The reclusive state has warned the United States of a nuclear attack in response to any aggression.

“We’ve all come to hear their words repeatedly, their word has not proven honest.”

According to Reuters, North Korea has also threatened to “lay waste to South Korea and Japan.”

On Friday, U.S. Defense Secretary Jim Mattis said that North Korea’s recent statements were provocative but should not be trusted as they have been proven to be hollow in the past. This is the statement was told at a news conference in Tel Aviv by Mattis before the latest threat to the U.S. aircraft carrier.

[Featured Image by Wong Maye-E/AP Images]