The state-run Korean Central News Agency, or KCNA, said the "relevant authority" is investigating Kim, a professor at the private Pyongyang University of Science and Technology, the New York Times reported.
On Sunday, Kim Hak Song became the fourth American citizen now jailed by the repressive regime, on charges such as espionage and "crimes against the state". No further details about his arrest or condition was given.
Hardly there is information available on Kim Jong-un's nuclear arsenal, other than what North Korean controlled media has released on it.
The U.S. State Department noted on Sunday that it was aware of the latest arrest.
On Friday, North Korea accused the USA and South Korean spy agencies of an unsuccessful assassination attempt on leader Kim Jong-un involving biochemical weapons.
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- American tourist Otto Warmbier was sentenced in March 2016 to 15 years in prison with hard labor for subversion.
Kim worked for Pyongyang University of Science and Technology, which is an unusual institution for North Korea.
The mixed signals have emanated from Washington after Pyongyang did not conduct another nuclear test on either of two important North Korean anniversaries in April, as had been widely expected. "When you are not credible about Syria, you're not credible about North Korea".
The university was founded by evangelical Christians and opened in 2010.
The US has dispatched a military strike group to Korean waters in order to hold military drills with Japan and North Korea.
Song is, however, fearful that Kim will invade South Korea.
North Korea has long sought direct diplomatic engagement with the United States over its nuclear weapons program and may now be arresting more USA citizens to incite the Trump administration to dispatch a high-level envoy to the country.
USA officials say North Korea must agree to give up its weapons programs if it wants formal talks to resume. But the vitriolic outrage over the alleged plan to assassinate Kim last month is also being doled out with an unusually big dollop of retaliation threats, raising a familiar question: What on Earth is going on in Pyongyang?