SEOUL, South Korea - A special envoy dispatched by President Obama launched a mission yesterday to coax North Korea to rejoin international talks on ending its nuclear programs - amid warnings of stronger sanctions if Pyongyang refuses.

Veteran diplomat Stephen Bosworth's visit is being closely watched for signs whether the reclusive communist country will return to the negotiating table after carrying out an atomic test blast in May and quitting the six-nation talks.

Bosworth arrived in the North Korean capital along with Washington's top nuclear negotiator, Sung Kim. Television footage showed the pair shaking hands with North Korean officials and posing for photos at a Pyongyang airport.

In Washington, State Department spokesman P.J. Crowley told reporters that Bosworth and his team likely would have two days of high-level talks but U.S. officials don't expect any communication with them until they leave North Korea.

Just before Bosworth began his mission, a senior U.S. official said bluntly the envoy was taking no new incentives.

"We don't intend to reward North Korea simply for going back to doing something that it had previously committed to do," the official told reporters, speaking on condition of anonymity for the background briefing.

He warned that the North faced strong U.N. sanctions if it did not agree to return to negotiations.

This week's talks - the first direct U.S.-North Korean discussions since Obama took office in January - come after a year of threatening rhetoric and rising tensions on the Korean peninsula.

Earlier this year, Pyongyang expelled U.N. nuclear inspectors, restarted its atomic facilities, test-fired a long-range rocket and a series of ballistic missiles, quit six-party talks, and conducted the nuclear test.

Now, North Korea has no choice but to rejoin the disarmament process since Washington has made it a condition of bilateral contact, said Koh Yu Hwan of Seoul's Dongguk University.

The regime in Pyongyang sees direct talks with Washington as a way of ensuring its survival and winning aid for rebuilding its moribund economy. This week's visit comes as North Korea is redenominating its national currency in an effort to curb runaway inflation and reassert its control on the economy.

Former nuclear envoy Christopher Hill was the last high-level U.S. official to visit for direct talks. He was in North Korea in October 2008.

Pyongyang says it needs nuclear bombs to counter the strong U.S. military presence in South Korea. The impoverished country has also used the atomic threat to win aid and other concessions from regional powers wary of their neighbor.

In recent months, the North has reached out to the United States and South Korea in an about-face that analysts said showed the regime was feeling the pain of U.N. sanctions.

Since August, the North has freed detained U.S. and South Korean citizens.