North Korea had freed three US detainees in May in an apparent goodwill gesture.
North Korea has decided to expel a US citizen who illegally entered the country last month, Pyongyang's official KCNA news agency said Friday.
The man, identified as Lawrence Bruce Byron, had been in custody after crossing into North Korea from China on October 16, it said.
"While being questioned, he said he had illegally entered the country under the command of the US Central Intelligence Agency," KCNA said.
"Relevant authorities have decided to expel him from the country," it added.
A man with the same name was arrested in South Korea while trying to sneak over the inter-Korean border in November last year.
Byron, who is in his late 50s and from Louisiana, was later deported back to the US.
Media reports said he told South Korean officials he sought to facilitate talks between North Korea and the United States, although he is a private citizen.
It is rare for North Korea to release an American detainee so swiftly and it comes amid stalled negotiations over Pyongyang's nuclear programme.
From journalists to missionaries, most Americans held by North Korea have been released after high-profile interventions.
The reclusive regime freed three US detainees in May in an apparent goodwill gesture before a summit between North Korean leader Kim Jong Un and US President Donald Trump in Singapore.
The three men travelled home with Secretary of State Mike Pompeo and were greeted by Trump on their arrival at an air base near Washington.
Currently, there are no known US detainees held by the rigid communist state.
At their historic Singapore summit, Trump and Kim signed a vaguely worded document on denuclearisation of the peninsula.
Progress has since stalled as Washington and Pyongyang spar over the meaning of the document.
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