North Korea's top court convicted two American journalists and sentenced them to 12 years in a prison Monday, intensifying the reclusive nation's confrontation with the United States.

The sentencing came amid soaring tensions fueled by the North's latest nuclear and missile tests. Many believe Pyongyang is using the journalists as bargaining chips as the U.N. debates a new resolution to punish the unpredictable country for its latest military threats.

In a cryptic two-sentence report, the North's state news agency said Laura Ling, 32, and Euna Lee, 36 were sentenced after the five-day trial ended Monday. They were guilty of a "grave crime" against the nation and of illegally crossing into North Korea, the Korean Central News Agency said.

The court "sentenced each of them to 12 years of reform through labor," said the report, without giving other details. The phrase refers to a prison term, according to Choi Eun-suk, a North Korean law expert at Seoul's University of North Korean Studies.

He said North Korean law calls for transferring convicts to prison within 10 days after verdict.

Ling and Lee, working for former Vice President Al Gore's California-based Current TV, cannot appeal because they were tried in North Korea's highest court, where decisions are final.

Some analysts believe negotiations will now begin that will likely lead to the journalists' release.

"North Korea refused to release them ahead of a court ruling because such a move could be seen as capitulating to the United States," said Hajime Izumi, professor of international relations and an expert on North Korea at the University of Shizuoka in Japan.

But now "North Korea may release them on humanitarian grounds and demand the U.S. provide humanitarian aid in return," he said. "North Korea will certainly use the reporters as a bargaining chip in negotiations with the United States."

Their release could come through a post-negotiation political pardon, said Yang Moo-jin, a colleague of Choi at the University of North Korean Studies.

Kim Yong-hyun, a professor at Seoul's Dongguk University, said the 12-year sentence _ the maximum possible allowed by the North's laws _ could have been a reaction to "hard-line" moves by the U.S., including threats of sanctions and putting North Korea back on a list of state sponsors of terrorism.

"But the sentence doesn't mean much because the issue will be resolved diplomatically in the end," he said.

Tensions have been running high since the North held its second underground nuclear blast May 25 and followed it up with several missile tests. U.S. officials have said the North appears to be preparing to test another long-range missile at a new launch pad.

The circumstances surrounding the trial of the two journalists and their arrest March 17 on the China-North Korean border have been shrouded in secrecy, as is typical of the reclusive nation. The trial was not open to the public or foreign observers, including the Swedish Embassy, which looks after American interests in the absence of diplomatic relations.

The two were reporting about the trafficking of women at the time of their arrest, and it's unclear if they strayed into the North or were grabbed by aggressive border guards who crossed into China.

U.S. State Department spokesman Ian Kelly said Washington was trying to confirm press reports of the sentencing.

Kelly said the U.S. was "deeply concerned" about the sentences and that officials would "engage in all possible channels" to free the women.

Gore spokeswoman Kalee Kreider said the former vice president has no comment. The South Korean government also did not comment. Alanna Zahn, a spokeswoman for the journalists' families, said the family members have no immediate comment.

Another American who was tried in North Korea in 1996 was treated more leniently. Evan C. Hunziker, apparently acting on a drunken dare, swam across the Yalu River _ which marks the North's border with China _ and was arrested after farmers found the man, then 26, naked. He was accused of spying and detained for three months before being freed after negotiations with a special U.S. envoy.

The North Koreans wanted Hunziker to pay a $100,000 criminal fine but eventually agreed on a $5,000 payment to settle a bill for a hotel where he was detained.

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Associated Press writers Jae-Soon Chang and William Foreman in Seoul, and Shino Yuasa in Tokyo contributed to this report.