Updated at 7:50 a.m. ET: SEOUL, South Korea -- 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.

Earlier on Sunday, South Korea said North Korea had moved a long-range ballistic rocket to its northwestern launch site in preparation for a launch, The Associated Press reported. North Korea has said it will launch a satellite into space on a long-range rocket next month as part of its peaceful space program.

Officials from the South Korean Defense Ministry and Joint Chiefs of Staff officials told the AP the information on the rocket came from the South Korean and U.S. militaries. They provided no further details and spoke on condition of anonymity, citing department rules.

Obama tells US troops at Korean DMZ: 'You guys are at freedom's frontier'

A White House official in South Korea told NBC News he could not confirm the rocket movement, saying he had not seen any U.S. intelligence reports on issue. Nobody would be surprised by such a provocation, however, the official added.

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

"It's like you're in a time warp," Obama said. "It's like you're looking across 50 years into a country that has missed 40 years or 50 years of progress."

From the DMZ, Obama returned to Seoul for a private meeting with South Korean President Lee Myung-bak. Both leaders warned there would be consequences if North Korea proceeds with its plans to launch the long-range rocket next month, a move the U.S. and other powers say would violate a U.N. ban on nuclear and missile activity because the same technology could be used for long-range missiles.

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

"Bad behavior 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."

The planned rocket launch is yet another setback for the United States 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.

'Strong and prosperous nation'
North Korea wants to use the celebrations around Kim Il Sung's birthday on April 15 to showcase its emergence as a "strong and prosperous nation," even as millions go hungry and it begs for international aid. The North has planned a series of events to mark the centenary of the birth of the state's founder, including a rare ruling party conference and the controversial launch of the ballistic rocket.

Its vow to fire the rocket has put in jeopardy a deal struck in February with the United States to get food aid in return for a moratorium on long-range missile and nuclear tests.

The North's Foreign Ministry warned that it was "intolerable double standards" for some countries to assert that the North was the only nation not allowed to launch satellites while for the same countries, satellite launches were commonplace.

Analysis: Why N. Korea's planned rocket test matters

"If there will be any sinister attempt to deprive the (North) of its independent and legitimate right and put the unreasonable double standards upon it, this will inevitably compel the (North) to take countermeasures," the ministry said in a statement late on Friday.

North Korea has conducted two similar launches. The last one, in 2009, provoked outrage in Tokyo because the rocket flew over Japan. As it did three years ago, Japan says it is prepared to shoot the rocket down if it threatens its territory.

The rocket launch, which the United States and other countries say is the same as a ballistic missile test, is banned under U.N. resolutions.

Even China, North Korea's main ally, has expressed its worry over the launch, scheduled for between April 12 and April 16, and has urged the North to "stay calm and exercise restraint and avoid escalation."

The secretive North has twice tested a nuclear device, but experts doubt whether it yet has the ability to miniaturize an atomic bomb to fit inside a warhead.

NBC News, Reuters and The Associated Press contributed to this report.

More from msnbc.com and NBC News:

• NBC: US pays close to $50,000 per Afghan shooting spree death
• North Korea moves long-range rocket to launch site, South says
• Obama calls Korean DMZ: 'Freedom's frontier'
• Bales charged with 17 counts of murder in Afghanistan massacre
• Iranian arms used against Syria protesters, officials say
• China struggles to contain wave of defiance in Tibet
• Landmark case: Nigerian villagers sue Shell over oil spills

Follow us on Twitter: @msnbc_world

AP file

The strong resemblance of Kim Jong Un (right) to his popular grandfather Kim Il Sung (left) may be subliminally creating warm feelings among his followers.

Photographs show he has his grandfather’s double chin and dark eyebrows, and his haircut supposedly is a throwback to the older man’s style in the 1940s. Some reports speculate that Kim Jong Un has even undergone plastic surgery to make him look more like his popular grandfather, North Korea founder Kim Il Sung, and less like his father, Kim Jong Il, who was not as well-liked.

Whether the resemblance to his grandfather has been inherited and/or surgically enhanced, it sure can’t hurt Kim Jong-Un, his late father’s handpicked successor to lead North Korea, psychologist Robert Bornstein says.  He'll likely benefit from the experience many of us have had of feeling warmly toward a person we’ve just met  simply because they resemble someone we like.

“We tend to prefer things that seem familiar over the things that seem unfamiliar, all other things being equal,” says Bornstein, a psychology professor at Adelphi University in Garden City, N.Y. “People will prefer a familiar-looking face over one that is less familiar.”

Psychologists call this phenomenon “the mere-exposure effect,” as in the mere exposure to someone or something leads to liking him or it. “It’s actually very powerful,” says Bornstein, who’s been studying the mere-exposure effect ever since he wrote his dissertation on it in the 1980s.

There are 300 to 400 studies in the scientific literature about the phenomenon, mostly having to do with visual and auditory--“things like voices, accents, the cadence of a person’s voice”--characteristics. “If it rings a bell, then we do have this initial reflexive response to it,” Bornstein says.

In other words, when it comes to North Korea dictators, like grandfather, like grandson.

But can familiarity breed contempt as well as warm fuzzies? Maybe, Bornstein says, although there haven’t been nearly as many studies of that question. But some research suggests that if you meet someone who reminds you of, say, a hated boss, “you have sort of a negative gut reaction to them,” Bornstein says, “and it can be hard to overcome, partly because gut reactions are so powerful.”

Have you had a rush of affection for a stranger just because they look like someone you care about? Tell us on Facebook.

KCNA via Reuters

Kim Jong-un, center, son of North Korean leader Kim Jong-il (not pictured) visits Mokran Video Company in Pyongyang in this official KCNA news agency photo
showing the heir apparent's slicked-back, high-sided haircut, which is a fashion hit in Pyongyang.

North Korean heir-apparent Kim Jong-un's slicked-back, high-sided haircut is a fashion hit in Pyongyang where young men are apparently queueing up for a similar cut.

Kim, believed to be in his late 20s and known as the "Young General," is packaged to look like his late grandfather, the secretive state's founder, Kim Il-sung.

The chubby youngest son of the current leader, Kim Jong-il, slicks his hair back at the top, and has it trimmed to the scalp to about an inch above the ears.

Completing the Kim Il-sung look, which experts say is designed to help win over the public's support for dynastic succession, the young Kim wears dark Mao-style suits.

The young Kim's haircut is dubbed a "youth" or "ambition" hairstyle in North Korea, South Korea's Chosun Ilbo newspaper has reported.

Earlier this week, North Korean state news agency KCNA quoted barber An Su-gil as saying the short-cut, medium-cut and square-cut hairstyles are now popular among young men.

North Korean newspaper Rodong Sinmun wrote in September that neat and short hair for young people makes them "captivating."

"A young man with (an) ambitious high sided haircut looks so sobering and stylish," the paper added.

South Korea's Yonhap news agency said that North Korean young men prefer short hairstyle for sanitary reasons, not just because they want to look neat and ambitious.

Kim Jong-un emerged as the reclusive North's leader-in-waiting last year when he was named a four-star general and given a prominent post within the ruling party.

This year he has regularly been photographed alongside his father during visits by foreign officials.

Read more content from msnbc.com and NBC News:

• Post-US Iraq: Welcome to Shia-stan
• Nazi hunters boost drive to find aging war criminals before they die
• North Korea's heir apparent's hair apparent as fashion hit
• UN chief defends NATO, calls for action on Syria
• Rebellious Chinese village under siege by police
• Iraqis unable to defend their borders as US exits