The BBC's John Sudworth in Seoul explains how events developed
North and South Korea fired dozens of artillery shells across their tense western sea border, in one of the most serious incidents since the Korean War ended without a ceasefire in 1953. Two South Korean soldiers were killed on Yeonpyeong island and more than a dozen people were hurt.
All times are in GMT
1600: That ends our live coverage following the exchange of fire between North and South Korea. For the latest developments, please go to our main news page.
1547: Robert Kelly, an assistant professor at Pusan National University in South Korea, tells the BBC World Service that Seoul's increasing global stature may have provoked Pyongyang. "My primary guess is that this is a response to the recent international prestige taken by South Korea at the G20. The G20 highlighted North Korean backwardness in the same way that it highlighted that South Korea was a partner of this global elite organisation, setting international rules and the North Korean's don't like this," he says.
1538: US defence department spokesman Col David Lapan says no additional US military assets would be moved into the region following Tuesday's incident in South Korea. It is also "too soon" to discuss ways the US might deter North Korea from another attacks, he adds.
1535: UN Secretary-General Ban Ki-moon is "deeply concerned by the escalation of tension on the Korean peninsula caused by today's artillery attack", his office says in a statement. "The secretary-general condemns the attack and calls for immediate restraint. The secretary-general regrets the loss of life and expresses sympathy to the victims and their families. The secretary-general insists that any differences should be resolved by peaceful means and dialogue."
1524: The UK's permanent representative to the United Nations, Sir Mark Lyall Grant, says there will be no meeting of the UN Security Council in New York on Tuesday. "No meeting has been requested," he is quoted as saying by the AFP news agency, apparently contradicting earlier comments by a French diplomat.
1515: Ben in Tokyo, Japan, says: "The footage of the attacks makes this qualitatively different from the attack on the [South Korean warship] Cheonan earlier this year. This is exactly what it would look like if North Korea shelled Incheon or Seoul, and regular South Koreans will feel the impact much more deeply. Diplomacy is important here not because it will solve the problem, but because it is the only hope to keep this from escalating."
Send us your comments
1511: Zhang Liangui, a North Korea expert at the Central Party School in Beijing, tells the Sydney Morning Herald that the North Korean heir apparent, Kim Jong-un, is deliberately destabilising the environment in order to mobilise the military and consolidate his power. He says the North also wants concessions from the South and to be acknowledged internationally as a nuclear state.
1459: A candlelight vigil is being held in Seoul for the two South Korean soldiers killed in the clashes.
1454: The Guardian newspaper has used a 2007 report by the US Congressional Research Service, to map out the 150 military incidents which have occurred between North and South Korea since 1958. North Korea v South Korea: every incident mapped
1445: Choi Jin-wook, a North Korea expert at the Korea Institute for National Unification in Seoul, tells the New York Times that the incident is a "sign of North Korea's increasing frustration" at the US government's refusal to remove sanctions. "Washington has turned a deaf ear to Pyongyang and North Korea is saying, 'Look here. We're still alive. We can cause trouble. You can't ignore us,'" he says. North Korea's most urgent priority is food aid, he adds.
1433: The South Korean unification ministry has said the country's Red Cross has "indefinitely" postponed a meeting with North Korean officials scheduled for Thursday on further reunions between family members separated since the Korean War. The ministry is also "reviewing the security situation" for South Korean workers at the Kaesong Industrial Park, a jointly operated facility in North Korea.
1427: Chung Min-lee, a South Korean foreign ministry expert, says he does not foresee the clashes escalating into a major war. "But if North Korea decides they want to push us a little bit further back by additional attacks on our territory, then we will respond militarily, including the possibility of taking out their artillery sites with our aircraft," he tells the Reuters news agency. "All eyes are firmly on ensuring that further escalation doesn't take place."
1423: Joseph Bolanos in New York City says: "North Korea continues to exhibit its military prowess with little or no consequence from the global community. As long as it fears no consequence to its warmongering, North Korea will continue to escalate its military taunts, at the risk and threat to innocent South Koreans and countries in the region." Send us your comments
1419: The New York Times reports that the South Korean Deputy Minister of Defence, Lee Yong-geul, has now acknowledged that artillery units were firing test shots on Tuesday afternoon close to the North Korean coast, from a battery on the South Korean island of Paeknyeongdo. But he denied that the shots crossed the disputed maritime border with North Korea.
1413: German Foreign Minister, Guido Westerwelle, has expressed his concern at the violence. "We appeal to all participants to contain themselves, and call for rationality and reconciliation to prevail. We would like to and can only request that all of the participants remain level-headed," he tells reporters.
1408: Brian Myers, a North Korea analyst based at South Korea's Dongseo University tells the BBC World Service that Pyongyang will not be too concerned about the international reaction. "I don't think they're going to take it particularly seriously. One of the common themes in North Korean propaganda is mockery of the outside world for talking very big but actually not carrying through on its threats. I think that's the kind of context they're going to put this in," he says.
1402: The BBC's diplomatic correspondent Jonathan Marcus says: From the North Korean viewpoint this is about establishing a deterrence strategy over the South and defending its vital interests. An annual South Korean military exercise is under way across the country. The North Koreans demanded that this be halted. And when it went ahead, for whatever reason, this clash erupted. North Korea seeks attention through show of power
1358: Yueliu in Beijing, China, says: "This situation is caused by the policies of the United States. The United States and South Korea should come back to the six party-talks instead of holding military exercises targeting North Korea or even China. The US should be responsible for the situation today, though we do not agree to North Korea's Kim's succession plan. Paper tigers are paper tigers." Send us your comments
1353: South Korea's foreign ministry says the shelling of Yeonpyeong violated the 1953 inter-Korean armistice, the United Nations Charter and other agreements that call for non-aggression between the two countries. "We have explained the current situation to all overseas missions and ordered them to remain on emergency alert," it says.
1347: Yonhap reports that hours after the incident, North Korea's leader, Kim Jong-il, and his youngest son, Kim Jong-un, toured a soy sauce factory and a medical school in Pyongyang.
1342: South Korean President Lee Myung-bak has ordered the military to retaliate against North Korea if there are "additional provocations", the Yonhap news agency reports. A presidential spokeswoman says Mr Lee has ordered strikes on a North Korean missile base near Yeonpyeong if further attacks take place on South Korean territory.
1336: Mr Bosworth also says he had a "useful" discussion in Beijing about the North's recently-revealed uranium enrichment facility. The discovery prompted the US to rule out the resumption of six-party talks on nuclear disarmament that Pyongyang abandoned two years ago. "We agreed on the essential need for us to continue co-ordination and consultation on this issue. We agree that a multilateral approach to the problems of North Korea remains essential."
1333: The US special representative to North Korea, Stephen Bosworth, says he has talked with Chinese officials in Beijing about the shelling of Yeonpyeong. "We both share a view that such conflict is very undesirable, and I expressed to them the desire that restraint be exercised on all sides and I think we agree on that," he adds.
1330: Tae Kim in Seoul says: "As the father of a newborn facing mandatory national guard training this Friday, this situation does quite scare me a bit. Of course, news outlets are highlighting military analysts' comments regarding their views that it is highly unlikely this will escalate into a full-scale war, but of course there is always the 'as long as North Korea does not continue or escalate their attack' comment. I decided to take the opportunity to discuss frankly with my wife what she should do for herself and our son if the situation escalates." Send us your comments
1315: The BBC's John Sudworth in Seoul says both sides are blaming each other, although given its record of previous provocations, North Korea will be seen by many neutral international observers as the likely culprit. Many will also wonder what this tells us about the murky internal politics of Pyongyang, in a period of risky transition as Kim Jong-il passes power to his youngest son.
1305: Japan describes North Korea's artillery attack as "unforgiveable", Reuters reports.
1305: The office of South Korea's president says in a statement: "The firing... constitutes an indisputable armed provocation against the Republic of Korea. Such actions will never be tolerated... The North Korean authorities will have to take full responsibility for the incident."
1300: Sam Kim in Seoul tweets: Returned from a quick meal. Streets as peaceful as they normally are. Only thing unusual was a radio relaying the news of attack in high tone.
Read Sam Kim's tweets
1258: Australia's Foreign Minister Kevin Rudd says: "I'm confident that President Lee Myung-bak will handle this appropriately. I'm less confident that the North Koreans are capable of handling these things competently. But we in Australia will stand in support of [South Korea's] response to this provocative act."
1253: ole999 emails from Russia: "North Korea is trying to distract its citizens from other issues. There is no smoke without a fire. I really hope this won't have any grave consequences."
1251: The United Nations Security Council could hold an emergency meeting in the next day or two to discuss the attack, a French diplomatic source is quoted by Reuters as saying.
1242: Robert Kelly of Pusan National University in South Korea tells BBC World Service he believes Pyongyang may have felt affronted by South Korea's high-profile recent staging of the G20 summit. North Korea does not like being made to feel like "the younger child" on the international stage... South Korea is extremely vulnerable - 50% of the population live within 50 miles of the demilitarised zone, and so retaliation by South Korea is very risky.
1238: The BBC's Steve Kingstone in Washington says US President Barack Obama was woken up just before 4am with the news. There is concern here about the situation. The Americans are pointing their finger firmly at North Korea. President Obama is expected to speak to South Korea's president shortly.
1224: Nato spokeswoman Carmen Romero tells the AFP news agency that the alliance "strongly condemns the North Korean shelling of a South Korean island and its resulting casualties. The alliance will carefully monitor developments with deep concern".
1205: Lee Choon-ok, a Yeongpyeong resident, says: "I was lying down and watching television, and I heard a bang, bang, bang sound. At first I thought the South Korean military was carrying out a very heavy artillery exercise since it had already announced earlier that it would carry out a military exercise this week. When the bomb went off near my house and when my house was damaged, then I realised that it was North Korea that had fired. I thought I would die if I stepped out of the house, so I stayed still."
1201: Eyewitness Shin Sung-hee says: "The artillery didn't just hit one location - there were fires everywhere and it was chaotic. I tried calling my wife at home, but I just heard "Darling", and the phone was disconnected. After about 10 minutes, the announcement was made saying that it was for real and telling the residents to evacuate to the shelter. I took my car and went back home. When I got there, my wife was standing outside and the house was already destroyed."
1154: French Foreign Minister Michele Alliot-Marie condemns the shelling of Yeonpyeong island, urging North Korea to end "provocations".
1140: The BBC's John Sudworth in Seoul says The North's accusation (that the South started firing) will be given very short shrift in the South Korean capital, with the government saying that it is the North who is responsible for a clear armed provocation.
1135: Daniel Butler tweets: "North Korea is like a spoilt child. You can issue empty threats of retaliation all you want but it won't learn."
Read Daniel Butler's tweets
1133: Secretary Kwon, attache at the Ministry of Defence in Seoul, tells BBC World Service: "Our military is reinforced, and is ready and prepared for any additional provocation from the North. The firing has now stopped. Civilians are in shelters."
1131: BBC defence and security correspondent Nick Childs says a key strategic calculation is that Seoul is within North Korean artillery range. Some 700,000 South Korean military personnel face more than a million in the North, with millions more reserves on both sides. And then there's the presence of some 30,000 US personnel in the South, meant as a deterrent to Pyongyang and a reassurance to Seoul.
1126: North Korea's military says: "The South Korean enemy, despite our repeated warnings, committed reckless military provocations of firing artillery shells into our maritime territory near Yeonpyeong island... [Pyongyang] will continue to make merciless military attacks with no hesitation if the South Korean enemy dares to invade our sea territory by 0.001mm."
1119: South Korea says it conducted test firing before the exchange at the island - but says it fired west not north, Reuters reports.
1115: EU top diplomat Baroness Catherine Ashton says in a statement: "I strongly condemn this attack by the DPRK (North Korea). I call on the North Korean authorities to refrain from any action that risks further escalation and to fully respect the Korean Armistice Agreement."
1111: South Korea says it was conducting a military drill in the area before North Korea fired, Reuters reports.
1107: Jung Hoon-lee, professor of international relations at Yonsei University in Seoul, tells BBC World Service: "If this is not an act of war, I don't know what is... We fired back in accordance with the rules of engagement. This is the bare minimum, one has to wonder are we really doing enough?"
1104: Dong Wook-kim in Seoul says: "I'm a soldier in the South Korean Army. I live in Seoul, but my military camp is located on the frontline with North Korea. I have to go back to my camp tomorrow so I am quite worried and anxious about this crisis. South Korean people are very angry. South Korea and the world have been giving a lot of chances to North Korea but they are always arrogant and attack South Korea. We must punish them. They are threatening world peace." Send us your comments
1058: Editor of Jane's Land-Based Air Defence magazine, Jim O'Halloran, tells BBC World Service that both sides are well-equipped militarily. Although the North has a lot of former Soviet equipment, much of this has been modernised and is in pretty good shape.
1048: Russian Foreign Minister Sergei Lavrov says: "It is necessary to immediately end all strikes. There is a colossal danger which must be avoided".
1045: Kim, a Yeonpyeong resident, tells Yonhap news agency: "I was at home when I was surprised by the sounds of bomb explosions. As I stepped out of my home, I saw the entire village had already turned into a sea of fire. I'm now staying in a shelter along with other villagers, but I'm still shaking with fear."
1039: David M tweets: "I live and teach in South Korea and the general opinion amongst us expats is, not again North Korea. Seems to happen every 6 months now."
Read David M's tweets
1030: Tomohiko Taniguchi, Japanese ex-foreign affairs spokesman tells BBC World Service: "Diplomacy has got to stop. The six-party dialogue framework is already history - that much is for certain."
He says pressure will mount on China to get tougher on North Korea.
1025: Junie in Seoul tweets: "Let's pray for Korea. It's all over TV now and my first time feeling that Korea is still technically at war. Hope everything turns out alright."
Read Junie Juju's tweets
1023:The BBC's John Sudworth in Seoul says there has been no sense of panic in the capital, although there are some signs of concern on financial markets.
1019: British Foreign Secretary William Hague says: "The UK strongly condemns North Korea's unprovoked attack... We strongly urge North Korea to refrain from such attacks and adhere to the Korean Armistice agreement."
1015: Jackson in South Korea says there is fear here. I live in Suwon. Most of the teachers I work with see it as a sign of war. Some are scared and are waiting for their recruiters to call them and tell them to get out of the country.
1010: Jasper Kim of Seoul National University tells BBC World Service: "It's a classic pattern from North Korea of sabre rattling. [North Korea is] trying to lure South Korea and its allies into some sort of larger skirmish, and the reason they want that is ultimately for bargaining power at the negotiating table."
1009: North Korea claims that South Korea fired first in Tuesday's clash, North Korean state media reports.
1006: Keir Thomas tweets: "I am an English ESL teacher in Ulsan, South Korea. My kids came into class today in a gloomy mood. Pretty downbeat."
Read Keir Thomas' tweets
1000: Russia's defence ministry tells Interfax that "the ministry is closely following the recent escalation of tension on the Korean Peninsula. However, no decision to put units of the Eastern Military District on high alert has been taken".
0950: South Korea's defence ministry says 17 soldiers and three civilians were injured in the shelling, according to Reuters.
0948: @antissa tweets: North Korea seeking respect, recognition and attention from major powers. Will it get it by bombing South Korea though?
0938: The White House says it "strongly condemns" the North Korean attack on South Korea, adding it is firmly committed to the defence of South Korea, regional peace and stability, Reuters reports.
0934: Sohn Young-jun in Seoul says Koreans think this event is different from past incidents, because the attack was aimed at Korean land where civilians live. People are afraid that there will be another war. We simply don't understand why North Korea is attacking us so seriously.
0932: A second South Korean marine dies after the shelling of Yeonpyeong, Yonhap news agency reports.
0925: @lihuizx tweets: What. People are praying for South Korea... Are the other Koreans not humans too? Are their lives worth anything less?
0923: BBC defence and security correspondent Nick Childs says that a flare-up like this inevitably sounds alarms, both literally and metaphorically, because of the potential trip-wire nature of the military stand-off between the Koreas.
0917: South Korea warns North Korea it will "sternly retaliate" for any further provocations, the presidential office says in a statement.
0915: @filmscorematt tweets: I hope china does something about North Korea before the rest of the world has to act. Neither of us would like a repeat of the Korean war.
0913: @anvanman tweets: The attack underlines North Korea's continuing intransigence in the face of international pressure on it to disarm and co-operate in a peace process.
0910: The BBC's diplomatic correspondent Jonathan Marcus says the shelling is both a wider demonstration to the outside world of North Korea's power and - many analysts believe - an indication of some kind of political transition at the very top of the North Korean power structure. There are strong indications that North Korea's leader Kim Jong-il has designated his son Kim Jong-un as his likely successor.
0857: Russia's foreign ministry says: "It is important that this does not lead to an aggravation of the situation on the Korean peninsula", Russia's Interfax news agency reports.
0850: Japanese Prime Minister Naoto Kan orders his cabinet "to make preparations so that we can react firmly, should any unexpected event occur".
0842:The BBC's John Sudworth in Seoul says fires are said to be burning out of control on Yeonpyeong island. There are reports of an evacuation under way.
0755:The BBC's Martin Patience in Beijing says China is North Korea's only major ally. The North Korean leader Kim Jung-il has visited the country twice this year. Beijing's economic and diplomatic support has been important in shoring up its isolated neighbour.
0745: China's Foreign Ministry spokesman Hong Lei expresses concern, urging both Pyongyang and Seoul to "do more to contribute to peace and stability in the region".
0732: South Korean President Lee Myung-bak orders officials to "sternly respond" to North Korea's action, but also urges to make sure the "situation does not escalate". Mr Lee is now holding a security meeting in a presidential situation room.
0700:The BBC's John Sudworth in Seoul says so far 80 shells have been fired in response according to the South Korean military, fighter jets have been scrambled and messages are being broadcast on the island instructing residents to take cover in secure positions.
0657: The first pictures from the scene show thick black smoke rising from burning homes on Yeonpyeong Island. There are reports of injuries to both civilians and soldiers.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.