1. Wide of the US President Barack Obama and South Korean President Lee Myung-bak entering for their joint news conference at the South Korean Presidential Office.

2. Mid of news conference

3. Close up of media

4. Mid of news conference

5. SOUNDBITE (English) Barack Obama, US President:

"Today, I simply say that North Korea will achieve nothing by threats or by provocations. North Korea know its obligations, and it must take irreversible steps to meet those obligations. On this, the United States and the Republic of Korea are absolutely united."

6. Close up of Obama

7. Wide of news conference

8. SOUNDBITE (English) Barack Obama, US President:

"North Korea's isolation damages further its relations with its neighbours and seriously undermines prospects of future negotiations."

9. Close up of media

10. Mid of news conference

11. SOUNDBITE (English) Barack Obama, US President:

"They need to understand that bad behaviour will not be rewarded. There had been a pattern, I think, for decades in which North Korea thought that if they act provocatively then somehow they would be bribed into ceasing and desisting acting provocatively. And President Lee and I have agreed from the start of our relationship that we are going to break that pattern."

12. Wide of news conference

13. SOUNDBITE (English) Barack Obama, US President:

"I think it's hard to have an impression of Kim Jong Un in part because the situation in North Korea still appears unsettled. It's not clear exactly who's calling shots and what their long term objectives are. But regardless of North Korean leadership, what is clear is that they have not yet made that strategic pivot where they say to themselves - what we are doing isn't working."

14. Wide of media

15. Wide of news conference

16. SOUNDBITE (Korean) South Korean President Lee Myung-bak:

"We both share our views that North Korea should immediately withdraw its plan to launch (the long range rocket) and follow the international duty. President Obama and I agreed to continue to strengthen the Korea-U.S. combined defence posture and sternly deal with any provocation and threat by North Korea."

17. Close up of officials

18. Mid of Obama and Lee

19. SOUNDBITE (Korean) South Korean President Lee Myung-bak:

"First, I was hoping to see Kim Jong Un being somewhat more open and showing a new kind of leadership. However, looking at current situation, I am a bit disappointed. I am going to wait and see how this changes in the future."

20. Close up of media

21. Close up of Obama and Lee

22. Wide of Obama and Lee exiting

23. Mid of Obama and Lee exiting

STORYLINE

Warning North Korea from its doorstep, President Barack Obama said Pyongyang risks deepening its isolation in the international community if it proceeds with a planned long-range rocket launch.

"North Korea will achieve nothing by threats or provocations," Obama said during a news conference Sunday in Seoul, South Korea, where he was to attend a nuclear security summit.

Obama spoke fresh off his first visit to the tense Demilitarised Zone, the heavily patrolled no-man's land between North and South Korea, where he peered long and hard at the isolated North.

Obama looked noticeably fatigued after essentially one long day that involved a 17-hour flight from Washington, a helicopter ride to

the border zone, two sets of diplomatic talks, the news conference and an official dinner.

From the DMZ, Obama returned to Seoul for a private meeting with South Korean President Lee Myung-bak and a joint news conference.

Both leaders warned there would be consequences if North Korea proceeds with its plans to launch a satellite using a long-range rocket next month, a move the U.S. and other powers say would violate a UN ban on nuclear and missile activity because the same technology could be used for long-range missiles.

Obama said the launch would jeopardise a deal for the US to resume stalled food aid to North Korea and may result in the tightening of harsh economic sanctions on the already-impoverished nation.

"Bad behaviour will not be rewarded," Obama said.

"There had been a pattern, I think, for decades in which North Korea thought if they had acted provocatively, then somehow they would be bribed into ceasing and desisting acting provocatively," he added.

The planned launch is yet another setback for the US in years of on-again, off-again attempts to launch real negotiations.

The announcement also played into Republican criticism that Obama had been too quick to jump at a new chance for talks with the North Koreans.

North Korea walked away from international disarmament talks in 2009. Years of fitful negotiations had succeeded in ending part of North Korea's nuclear program but failed in stopping it from building and testing nuclear devices and long-range missiles that might be able to carry bombs.

The United States is a party to the stalled talks, along with China, Japan, Russia and South Korea. The negotiations were aimed at offering North Korea economic and diplomatic incentives to give up threatening elements of its nuclear program.

Obama's trip comes as North Koreans mark the end of the 100-day mourning period for longtime leader Kim Jong Il, who died of a heart attack in December. Since Kim's death, son Kim Jong Un has been paying a series of high-profile visits to military units and made his own trip to the "peace village" of Panmunjom inside the DMZ

earlier this month.

Obama said he had not yet been able to make a full assessment of the North's new leader, saying the political situation there appeared to be "unsettled."

"It's not clear exactly who is calling the shots and what their long-term objectives are," Obama said.

Lee, too, said it was "premature" to assess the North's new leader. He said that while he had some expectations that the young Kim might take a different approach than his father, he found news of the rocket launch to be a "disappointment."

1. Wide of Yu Woo-ik, South Korean Unification Minister, arriving at "Global Forum on North Korean Economy"

2. Close-up of Yu

3. Wide of Yu on stage delivering speech

4. Cutaway of forum delegates

5. SOUNDBITE: (Korean) Yu Woo-ik, South Korean Unification Minister:

"North Korea's long-range rocket launch is a grave, provocative act and a serious security threat against South Korea and the international community. I cannot help a feeling of regret in relation to the North Korean regime's senseless attitude. Ignoring the reality, in which North Korean people are becoming refugees crossing the border to come to a foreign country, after suffering from political oppression and starvation, and enforcing the long-range rocket launch, which is an enormous expense."

6. Close-up of delegates

7. Wide of Yu on stage delivering speech

8. SOUNDBITE: (Korean) Yu Woo-ik, South Korean Unification Minister:

"Even though North Korea's action is very disappointing, the South Korean government will not fall short on expectations of the common benefit and mutual prosperity of the South Korea-North Korea relationship. We ask for our people to remain patient, and we are going to continue to open the door for dialogue."

9. Wide of delegates

10. Mid of Yu bowing after speech and turning to walk off stage

11. Wide of Yu shaking hands with forum delegates after speech

SCRIPT

A senior South Korean official has described North Korea's plans to launch a rocket as a "grave, provocative act" and a "serious security threat."

Speaking at a forum on North Korea's economy in Seoul on Wednesday, Unification Minister Yu Woo-ik described Pyongyang's attitude as "senseless."

North Korea announced on Friday that it would fire an observation satellite into space on a new rocket as part of celebrations next month to mark the 100th anniversary of late President Kim Il Sung's birth.

Kim's grandson, Kim Jong Un, has led the nation of 24 (m) million since his father, Kim Jong Il, died in December.

The US, Japan, Britain and others have urged North Korea to cancel the planned launch, calling it a threat to diplomatic efforts, and warning that it would violate a UN ban on nuclear and missile activity because the same rocket technology can be used for long-range missiles.

North Korea argues that such launches are part of a peaceful space programme that is exempt from any disarmament agreements.

It said the launch would be a test of satellite technology.

Yu urged South Koreans to "remain patient" and said that "we (South Korea) are going to continue to open the door for dialogue."

The US has warned that a deal to resume stalled food aid to the North could be jeopardised if North Korea goes ahead with the launch.

US President Barack Obama plans to visit the Demilitarised Zone (DMZ) separating North and South Korea at the start of an international trip next week, the White House said on Tuesday.

The DMZ trip is Obama's first stop on a three-day visit to Seoul, South Korea, for an international summit on keeping nuclear weapons materials out of the hands of militant extremists.

North Korea has built and tested nuclear devices and is suspected in the spread of weapons of mass destruction to other countries.

North Korea is not invited to the security gathering.