North Korea said Thursday it had sentenced a Korean-American tour operator to 15 years' hard labour for "hostile acts", stoking tensions with the United States which had pleaded for his release.
Kim Jong-Un's isolated regime is likely to use the detainee as a bargaining chip, experts said, as it seeks concessions from the United States following weeks of bellicose threats of missile strikes and of nuclear war.
Pae Jun-Ho, known in the United States as Kenneth Bae, was arrested in November as he entered the northeastern port city of Rason. He has been accused of trying to "topple the DPRK" (North Korea).
"The Supreme Court sentenced him to 15 years of compulsory labour for this crime," according to the North's official Korean Central News Agency (KCNA), which said his trial was held on April 30.
Pyongyang has not specified the basis of the offences allegedly committed by Bae, who is reported to be aged 44, but KCNA has previously said that he admitted his crimes.
Seoul-based activist Do Hee-Yoon has told AFP that he suspected Bae was arrested because he had taken photographs of emaciated children in North Korea as part of efforts to appeal for more outside aid.
The United States had urged North Korea to free the detainee on "humanitarian grounds", pointing out that he entered the country on a valid visa.
A senior US State Department official said Washington was "working to confirm the reports" of Bae's sentence through the Swedish embassy, which represents US interests in the North in the absence of diplomatic ties.
US politician Bill Richardson failed to secure Bae's release when he visited North Korea in January with Google chairman Eric Schmidt.
Richardson, a former New Mexico governor and ex-ambassador to the United Nations, was unable to even meet Bae during his trip, which was criticised by Washington as ill-timed following Pyongyang's rocket launch in December.
Tensions have been running high between the United States and North Korea since Pyongyang carried out a third nuclear test in February.
The North reacted furiously to the use of nuclear-capable B-52s and B-2 stealth bombers in recent joint US-South Korean military drills.
In a commentary published on Thursday, KCNA blamed the United States for the current standoff.
"The escalating tension on the Korean Peninsula is entirely attributable to the US heinous hostile policy toward the DPRK," it said.
"The US is seriously mistaken if it thinks it can cover up its sinister scenario by talking about dialogue though it is the arch criminal who drove the situation to the brink of a nuclear war."
Several Americans have been held in North Korea in recent years.
In 2011 a US delegation secured the release of Eddie Jun Yong-Su, a California-based businessman who had been detained for apparent missionary activities.
In 2010 former US president Jimmy Carter won plaudits when he negotiated the release of American national Aijalon Mahli Gomes, sentenced to eight years of hard labour for illegally crossing into the North from China.
On another mercy mission a year earlier in 2009, former president Bill Clinton won the release of US television journalists Laura Ling and Euna Lee, jailed after crossing the North Korean border with China.
Experts believe the North is likely to try to use Bae to extract concessions from Washington.
"The North will surely try to take advantage of Kenneth Bae as a bargaining chip in negotiations with the US," said Yang Moo-Jin, a professor at the University of North Korean Studies in Seoul.
"But the whole atmosphere is quite different from when similar hostage disputes erupted in the past. The diplomatic and military situation is so tense that the US is unlikely to dramatically change its stance or try to open dialogue with the North just to save this guy," he said.
Last month Pyongyang demanded an end to UN sanctions and to US-South Korean military drills in exchange for talks -- conditions that Seoul dismissed as "absurd".