North Korean leader Kim Jong-il (2nd L) and his son Kim Jong-un (L) visit the newly-built Soy Sauce Shop at the Ryongsong Foodstuff Factory in North Korea, in this undated picture released by North Korea's official KCNA news agency on November 24, 2010. 
 
 SEOUL | 
 
 SEOUL (Reuters) - North Korean leader Kim Jong-il and his son and successor Jong-un visited the artillery base from where shells were fired at a South Korean island just hours before the attack, South Korean media reported on Thursday. 
 
 North Korea's attack on Yeonpyeong Island that killed two South Korean marines and two civilians on Tuesday was probably ordered by Kim Jong-il himself, the Joongang Daily quoted a well-informed government source as saying. 
 
 Seoul government officials contacted by Reuters could not comment on the reports. 
 
 The United States says it believes North Korea's actions were an isolated act tied to leadership changes in Pyongyang, and many experts say the North carried out the shelling to burnish the image of the inexperienced and little-known younger Kim. 
 
 The ailing leader is desperate to give a lift to his youngest son, named as heir apparent to the family dynasty in September, but who has little clear support in the military. 
 
 South Korean media reported the father and son had met General Kim Kyok-sik, the commander of the frontline fourth corps in charge of a Navy base in South Hwanghae province, just before the North shelled the island. 
 
 A member of the National Assembly's Defense Committee said military intelligence obtained the information and was trying to figure out whether the visit was directly related to the attack, the Chosun Ilbo reported. 
 
 Just before the sinking of a South Korean warship in March, the South Korean military "had confidential information that Kim Jong-il met Kim Yong-chol, the director of the general reconnaissance bureau at the People's Armed Forces, so now it's focusing on the possibility of Kim Jong-il and his son approving the shelling of Yeonpyeong while meeting with Kim Kyok-sik," he said. 
 
 JoongAng Daily quoted a source as saying that Kim visited the coastal artillery base in Gaemori from where the shells were fired with his son a day before the attack. 
 
 "This is circumstantial evidence that the attack was meticulously planned (by North Korea) beforehand," said the source. 
 
 North Korea's official Korean Central News Agency issued a report on Monday saying Kim Jong-il had made a trip to a fish farm in Yongyon, South Hwanghae province, and that he was accompanied by top military brass, including Jong-un. 
 
 There was no mention of any visit to military sites. 
 
 Yongyon is just a few kilometers from the North Korean coastal military base where the artillery was fired from, reports said. 
 
 North Korea has entered a potentially long and unpredictable period of leadership transition, with the elevation of Kim's youngest son to the rank of general in a clear signal he is the chosen successor. 
 
 The media has begun celebrating Kim Jong-un as "the young general" -- even though his military experience appears to be zero. 
 
 Analysts have been warning since September that North Korea would likely carry out an act of brinkmanship to boost the younger Kim's standing, to mirror the iron rule of his father. 
 
 (Editing by Raju Gopalakrishnan and Andrew Marshall) ||||| South Korea's president vowed Thursday to boost security around islands near the site of a North Korean artillery attack while the North warned of more retaliation if the South carries out any "reckless military provocations." 
 
 A South Korean resident walks by destroyed houses on Yeonpyeong island, South Korea, Thursday, Nov. 25, 2010. South Korean troops remained on high alert, and the country's Cabinet held a special meeting... (Associated Press) 
 
 South Korean President Lee Myung-bak takes a moment of silence for South Korean marines and civilians killed in a North Korean bombardment during an emergency meeting of top security officials and economy... (Associated Press) 
 
 South Korean President Lee Myung-bak, second from right, and ministers take a moment of silence for South Korean marines and civilians killed in a North Korean bombardment during an emergency meeting... (Associated Press) 
 
 South Korean marines take a moment of silence for fellow soldiers killed in Tuesday's North Korean bombardment on Yeonpyeong island during a memorial service at a military hospital in Seongnam, South... (Associated Press) 
 
 A South Korean reporter walks by destroyed houses following Tuesday's artillery barrage by North Korea on Yeonpyeong island, South Korea, Thursday, Nov. 25, 2010. (AP Photo/Yonhap, Park Ji-ho) KOREA... (Associated Press) 
 
 South Korean President Lee Myung-bak, center, speaks during an emergency meeting of top security officials and economy ministers to discuss measures for North Korea's artillery attack on the South's Yeonpyeong... (Associated Press) 
 
 South Korean President Lee Myung-bak, second from left, speaks during an emergency meeting of top security officials and economy ministers to discuss measures for North Korea's artillery attack on the... (Associated Press) 
 
 Kim Oh-bock, right, mother of Seo Jeong-woo, a Marine who was killed on South Korea's Yeonpyeong Island following Tuesday's attack by North Korea, weeps during a memorial service at at a military hospital... (Associated Press) 
 
 A South Korean reporter walks by destroyed houses following Tuesday's artillery barrage by North Korea on Yeonpyeong island, South Korea, Thursday, Nov. 25, 2010. (AP Photo/Yonhap, Park Ji-ho) KOREA... (Associated Press) 
 
 Kim Oh-bock, mother of Seo Jeong-woo, a Marine who was killed on South Korea's Yeonpyeong Island after it was shelled by North Korea, weeps during a memorial service at a military hospital in Seongnam,... (Associated Press) 
 
 Seoul and Washington also increased pressure on China to use its influence on ally North Korea to ease soaring tensions that erupted after an exchange of fire Tuesday that left four South Koreans dead _ including two civilians. China urged both sides to show restraint. 
 
 The North's bombardment of a tiny South Korean island along a disputed maritime frontier has alarmed world leaders including President Barack Obama, who reaffirmed plans for joint maneuvers with Seoul in the Yellow Sea starting Sunday. 
 
 "We should not let our guard down in preparation for another possible North Korean provocation," South Korean President Lee Myung-bak said during an emergency meeting on security and economic repercussions from the attack, according to Yonhap news agency. 
 
 The U.S.-South Korean drills involving aircraft carrier USS George Washington, although previously scheduled, are sure to infuriate North Korea. The North made no specific mention of those exercises in its statement but warned that its military would "launch second and third strong physical retaliations without hesitation if South Korean warmongers carry out reckless military provocations." 
 
 The North's statement said Washington was to blame for South Korean artillery exercises earlier in the week near disputed waters which prompted the North to respond with its artillery barrage on Yeongpyeong island Tuesday. 
 
 Washington "should thoroughly control South Korea," it said. The warning was issued by North Korea's military's mission at the truce village of Panmunjom and was carried by the country's official Korean Central News Agency. 
 
 The Obama administration urged China to rein in its ally North Korea, with the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, saying, "We really think it's important for the international community to lead, but in particular China." 
 
 Chinese Premier Wen Jiabao called on all sides to show "maximum restraint" over recent tensions on the Korean Peninsula and says his country opposes military provocations of all forms. 
 
 Wen also urged the international community to work to ease tensions. He repeated Chinese calls for renewed six-nation talks aimed at persuading North Korea to dismantle its nuclear programs. 
 
 Wen said those talks, involving the two Koreas, China, Russia, Japan and the United States, are the best way to ensure stability on the peninsula and its denuclearization. 
 
 Wen's remarks were made in Russia on Wednesday on a state visit and posted on the Chinese Foreign Ministry's website. 
 
 South Korea said it will increase diplomatic efforts toward China to secure Beijing's help over North Korea's provocation, according to Yonhap. Repeated calls to the presidential office seeking confirmation went unanswered. 
 
 Residents of Yeongpyeong who evacuated the island and began arriving at the South Korean port of Incheon on Wednesday told harrowing tales of fiery destruction and narrow escapes. 
 
 Ann Ahe-ja, one of hundreds of exhausted evacuees from Yeonpyeong island arriving in the port of Incheon on a rescue ship, said the artillery barrage that killed four people _ two of them civilians _ had caught her by surprise. 
 
 "Over my head, a pine tree was broken and burning," Ann told AP Television News on Wednesday. "So I thought 'Oh, this is not another exercise. It is a war.' I decided to run. And I did." 
 
 About 10 homes suffered direct hits and 30 were destroyed in the midafternoon barrage, according to a local official who spoke by telephone from the island just seven miles (11 kilometers) from the North Korean shore. About 1,700 civilians live on Yeonpyeong alongside South Korean troops stationed there. 
 
 "I heard the sound of artillery, and I felt that something was flying over my head," said Lim Jung-eun, 36, who fled the island with three children, including a 9-month-old strapped to her back. "Then the mountain caught on fire." 
 
 Many of those evacuated from Yeonpyeong had spent the night in underground shelters and embraced tearful family members on arrival in Incheon. 
 
 The shower of artillery from North Korea was the first to strike a civilian population. In addition to the two marines killed, the bodies of two men, believed in their 60s, were pulled from a destroyed construction site, the coast guard said. At least 18 people _ most of them troops _ were injured. 
 
 Officials in Seoul said there could be considerable North Korean casualties. North Korea's main Rodong Sinmun newspaper published a military statement accusing South Korea of triggering the exchange, but did not mention any casualties.
– North Korea has warned it will attack the South again if it carries out any "reckless military provocations." The statement from a North Korean military delegation—which promised "second and third strong physical retaliations without hesitation"—didn't specifically mention the US-South Korea joint military exercises set to begin on Sunday, but the drills are certain to infuriate Pyongyang, the AP notes. The statement blamed the US as well as the South for the artillery attack, because at the end of the Korean War, the US drew a border in the Yellow Sea which the North refuses to recognize. South Korean media say North Korean leader Kim Jong-il and his son and successor Jong-un visited the artillery base from where the South was attacked several hours before the shells were launched, Reuters reports.