SEOUL, South Korea - U.S. and Japanese officials gave starkly different assessments Friday of key trade negotiations, as President Obama left Tokyo without a final agreement on a deal to improve access to Japanese markets for U.S. producers.

A senior Obama administration official said the two countries had achieved a "breakthrough" in their effort to help advance a broader, 12-nation free-trade accord known as the Trans-Pacific Partnership (TPP).

As Obama flew from Tokyo to Seoul, the official told reporters on Air Force One that negotiators had set "parameters" for continued talks that could lead to an agreement.

But Akira Amari, a Japanese state minister in charge of the trade talks for Prime Minister Shinzo Abe's administration, said in Tokyo that several issues were still unresolved.

"We made significant progress, but our positions are still far apart," Amari told reporters. "We'll continue talks."

The White House views the TPP - whose 12 negotiating countries account for 40 percent of global gross domestic product - as a critical component of Obama's strategy to shift U.S. foreign policy engagement toward the Asia-Pacific.

But the trade negotiations have faced intense opposition in both countries. Senate Democrats blocked Obama's bid in Congress to gain "trade promotion authority," which would have allowed him to negotiate a deal without lawmakers changing the terms later. Democrats have looked skeptically at the trade deal amid strong opposition from labor unions and environmental groups.

Thea Lee, deputy chief of staff at the AFL-CIO, scoffed Friday at the White House's contention that a breakthrough had been made. "For one party to say they've made terrific progress afterward is a little like window dressing," she said, adding that the inability to secure a deal is "good news because these talks are way off track."

Meeting with South Korean President Park Geun-hye, Obama first proposed holding a moment of silence to honor the men and women who lost their lives in this month's accident. Then he offered Park an American flag as a sign of Americans' sympathy for the loss of "so many young people, students who represented the vitality and the future of this nation."

A few hours before, Obama laid a wreath in honor of those Americans who died in the Korean War at the National War Memorial adjacent to the Yongsan U.S. Army garrison.

As Obama was visiting South Korea, state media in rival North Korea said authorities there have detained a 24-year-old American man for improper behavior while he was being processed to enter the country as a tourist.

The Korean Central News Agency identified the man as Miller Matthew Todd - possibly putting his surname first - and said he entered the country April 10 with a tourist visa, but tore it up and shouted that he wanted to seek asylum. The brief report said he chose the North "as a shelter." It said he was detained for "gross violation" of North Korea's legal order and was being investigated.

In Washington, State Department spokeswoman Jen Psaki told reporters that the U.S. is aware of the report, but she did not confirm an American was being held.