Foreign governments have focused intense scrutiny on North Korea since Kim's death was announced Monday because of concerns over his untested heir's rise in a country with a nuclear program, 1.2-million strong military and a history of deep animosity toward its neighbors.
But the capital remained a scene of mourning - not protest - on Thursday. U.S. and South Korean military officials said there had been no unusual military movements by the North Koreans in recent days.
"This appears to be a relatively smooth transition on the peninsula, and we hope it stays that way," Pentagon spokesman George Little said in Washington, adding that there has been no increase in force protection levels for U.S. troops in South Korea.
South Korean President Lee Myung-bak sought to assure Pyongyang that his country was "not hostile," despite putting its front-line troops on alert since Kim's death was announced.
South Korean Defense Ministry spokesman Yoon Won-sik said North Korea's military isn't showing any particular movement and that the South's troops are operating normally despite the alert.
In a clear signal to North Korea's people and the outside world, the North's main newspaper Rodong Sinmun in a lengthy editorial urged the country to "rally, rally and rally behind great comrade Kim Jong Un and faithfully uphold his leadership."
It called him "the outstanding leader of our party, military and people and a great successor."
Ratcheting up the personality cult it builds around the Kim family, North Korea claimed that Kim Jong Il's death generated a series of spectacular natural phenomena, creating a mysterious glow atop a revered mountain, cracking a sheet of ice on a lake with a loud roar and inspiring a crane to circle a statue of the nation's founder before perching in a tree and drooping its head in sorrow.
Dramatic scenes of mourning in the capital have continued nearly nonstop since Monday's announcement of Kim's death, which the government says happened two days earlier when he suffered a massive heart attack while on a train.
On Thursday, a long line of North Koreans filed past the body of Kim Jong Il, which lay in state in the Kumsusan Memorial Palace. With a military band playing a funeral dirge and a flag flying at half staff above the palace, mourners in black suits slowly circled Kim's glass coffin, Kim's head and shoulders bathed in a spotlight, a red cloth pulled tight around his body.
Outside powers, including the United States, Japan and South Korea, are watching with keen interest to see how the transition proceeds.
Communication between the United States and North Korea still appears open as the North continues its official 11-day mourning period. This is in sharp contrast to the confusion that followed the death of North Korean founder Kim Il Sung in 1994 and an indication that discussions may resume after the mourning period on food aid and efforts to rid North Korea of its nuclear arms programs.
The State Department said it wasn't expecting any meeting with the North Koreans this week, and little contact before the mourning period ends Dec. 29.
"We want to be respectful of the period of mourning, but the ball's in North Korea's court," State Department spokeswoman Victoria Nuland told reporters. "We are also appreciative that this is not a moment in Pyongyang where we're likely to have fresh instructions until after the mourning period."
South Korea sent its nuclear envoy to China on Thursday for talks on ways to restart international negotiations to rid North Korea of its nuclear programs.
Despite the signs that North Korea is consolidating power behind Kim Jong Un, fears of instability remain high.
Chinese boatmen along a river separating North Korea and China told The Associated Press that North Korean police have ordered them to stop giving rides to tourists, saying they will fire on the boats if they see anyone with cameras.
Kim Jong Un only entered the public view last year and remains a mystery to most of the world.
South Korea's intelligence agency has told Parliament members that an ad hoc committee in which Kim Jong Un is a vice chairman is expected to handle key state affairs before he formally becomes the country's leader.
The agency predicts Kim Jong Un's aunt Kim Kyong Hui, a key Workers' Party official, and Jang Song Thaek, her husband and a vice chairman of the powerful National Defense Commission, will play larger roles supporting the heir, according to a lawmaker who spoke to the AP.
Reporting from Pyongyang by Associated Press Television News senior video journalist Rafael Wober. AP writers Foster Klug, Hyung-jin Kim, Sam Kim and Eric Talmadge in Seoul, South Korea, Lolita Baldor in Washington, and Korea bureau chief Jean H. Lee contributed to this story.