North–South Korea artillery engagement
The Bombardment of Yeonpyeong () was an artillery engagement between the North Korean military and South Korean forces stationed on Yeonpyeong Island on 23 November 2010. Following a South Korean artillery exercise in disputed waters near the island, North Korean forces fired around 170 artillery shells and rockets at Yeonpyeong Island, hitting both military and civilian targets.
Shelling caused widespread damage on Yeonpyeong. South Korea retaliated by shelling North Korean gun positions. In total, between four and 20 people (military personnel and civilians) were killed on both sides and approximately 40–55 people were wounded. 
The North Koreans subsequently stated that they had fired in response to South Korean artillery firing into North Korean territorial waters.
The incident caused an escalation of tension on the Korean Peninsula and prompted widespread international condemnation of the North's actions. The United Nations declared it to be one of the most serious incidents since the end of the Korean War, and former US ambassador to the UN Bill Richardson said tensions had escalated to become "the most serious crisis on the Korean peninsula since the 1953 armistice, which ended the Korean War".
Background.
A western maritime line of military control between the two Koreas was established by United Nations Command (UNC) in 1953, called the Northern Limit Line (NLL). which is a maritime boundary that demarcates the territorial waters of South and North Korea in the West Sea. The boundary line extends from the Military Demarcation Line (MDL) into the sea, running between the mainland portion of Gyeonggi-do province, historically part of Hwanghae before 1945, and the adjacent offshore islands, including Yeonpyeong and Baengnyeongdo. 
The UNC established the NLL in 1953 as a Western maritime line of military control following the Korean War. However, its proximity to the North Korean mainland has resulted in prolonged tension and disputes over territory and fishing rights in the area. Straddling between peace and conflict According to "Time," "The North does not recognize the border that was unilaterally drawn by the United Nations at the close of the 1950–53 Korean War." Under the armistice, the United Nations has designated five Northwest Islands to remain within its jurisdiction - Baengnyeongdo, Yeonpyeongdo, Daecheongdo, Socheongdo, and Udo. These islands strategically lie in the Yellow Sea just off the North Korean coast, causing disputes over their control and posing a persistent security threat to South Korea. The countries' western maritime boundary has long been a flash point between the two Koreas.
North Korea did not dispute or violate the line until 1973. The NLL was drawn up at a time when a three-nautical-mile territorial waters limit was the norm, but when in the 1970s a twelve nautical mile limit became internationally accepted, the implementation of the NLL prevented North Korea, in areas, from accessing, arguably actual or prospective, territorial waters. Later, after 1982, it also hindered North Korea establishing a United Nations Convention on the Law of the Sea Exclusive Economic Zone to control fishing in the area.
In 1999, North Korea drew up their own line, the "West Sea Military Demarcation Line" which claims a maritime boundary farther south that encompasses valuable fishing grounds (though it skirts around South Korean-held islands such as Yeonpyeong). This claim is not accepted by either South Korea or the United Nations Command.
The United Nations Command perspective remained unchanging, explaining that the NLL must be maintained until any new maritime military demarcation line could be
established through the Joint Military Commission on the armistice agreement. 
In an effort to assert its territorial claims, North Korea has pursued a strategy of challenging South Korean control of the waters south of the NLL. It has made several incursions that have sparked clashes between the two sides, notably a naval battle near Yeonpyeong island in 1999 as well as another engagement in the same area in 2002. Although there were no further serious clashes for a time, in 2009 increasing tensions along the disputed border led to a naval battle near the island of Daecheong, and accusations that a North Korean submarine had sunk the South Korean corvette "Cheonan" off Baengnyeong Island in March 2010.
The Northern Limit Line (NLL) is not officially recognized by North Korea, and as a result, its fishing boats regularly operate close to or over the line, escorted by North Korean naval vessels. This has led to confrontations between North and South Korean navy ships, further heightening tensions in the area.
However, on April 27, 2018, North Korea and South Korea adopted the Panmunjom Declaration for Peace, Prosperity, and Unification of the Korean Peninsula. As part of this agreement, areas surrounding the Northern Limit Line were designated as a maritime peace zone, intended to prevent accidental military clashes and ensure safe and sustainable fishing activities for both countries. This landmark agreement brought hope for a peaceful resolution to the long-standing conflict over the NLL, although its implementation is yet to be fully realized.
Days before the incident, the North Korean government revealed their new uranium enrichment facility, prompting the South Korean government to consider requesting that the United States station tactical nuclear weapons in South Korea for the first time in 19 years. On the same day, South Korea and the United States began the annual Hoguk exercise, a large-scale military drill involving the South Korean and US militaries. The 2010 exercise involved 70,000 troops from all four branches of the South Korean military, equipped with 600 tracked vehicles, 90 helicopters, 50 warships, and 500 aircraft. The United States contributed its 31st Marine Expeditionary Unit and the Seventh Air Force to the land and sea elements of the exercise.
It had originally been intended that the United States Navy and Marine Corps would participate in a joint amphibious exercise in the Yellow (Western) Sea, west of South Korea. However, the US pulled out of the joint exercise citing "scheduling conflicts", though South Korean observers suggested that the real reason was the opposition of China, which regards a large portion of the Yellow Sea as its own territory. The North Korean government regards the exercises as preparation for a combined arms attack on the North.
Engagement.
On the morning of 23 November 2010, North Korea reportedly "wired a complaint [to the South] ... asking whether (the [Hoguk] exercise) was an attack against the North." It warned that it would not tolerate firing in what it regarded as its territorial waters. South Korean forces went ahead with a live-fire exercise in waters off Baengnyeong Island and Yeonpyeong Island within South Korean-held territory.
According to a South Korean military official, shells fired as part of the exercise were directed at waters in the south, away from North Korea. A Marine colonel on the island indicated the shells had been fired towards the southwest. South Korean Minister of National Defense, Kim Tae-young, said the firing was not part of the Hoguk exercise, but was a separate routine monthly drill carried out 4–5 km away from the NLL, contrary to previous media reports. The usual firing range is by in size and runs parallel to the NLL to the south-west of Yeonpyeong Island, and is largely within North Korea's territorial waters claimed in 1955.
At 14:34 local time, North Korean coastal artillery batteries on Mudo, and a recently redeployed 122-mm MRL at Kaemori, in North Korea's South Hwanghae Province, opened fire on the island of Yeonpyeong. The bombardment took place in two waves, from 14:34 to 14:55 and again from 15:10 to 15:41. Many of the shells landed on a military camp, but others hit the island's principal settlement, destroying numerous homes and shops, and starting fires. About 108 shells were fired total, according to a North Korean defector who had served in an artillery battery.
Three of the six K9 Thunder 155 mm guns stationed on Yeonpyong returned fire, while two were damaged and one blocked by a dud shell. South Korean artillery fired 80 shells in total. Initially, the South Koreans targeted barracks and command structures on Mudo, but began firing at the MRL at Kaemori about thirteen minutes later, due to the AN/TPQ-37 counter-battery radar not properly functioning, which meant the guns initially targeted general locations, such as the barracks.
South Korean KF-16 and F-15K jets were also scrambled to the area, though they did not engage North Korean targets, as the North Korean artillery did not start a third barrage. South Korean counterstrikes ended at 16:42. It was the first artillery battle to take place between North and South Korea since the 1970s and was seen as one of the most serious attacks by the North on the South since the 1953 Armistice.
With power on Yeonpyeong knocked out and several fires breaking out as a result of the North Korean shelling, the South Korean military ordered civilians to evacuate to bunkers.
08:20: North sends a telex message requesting a halt to the South's artillery training exercise.
10:00: South starts the artillery training exercise.
14:30: North deploys five MiG-23ML fighters from the 60th Regiment at Pukchang Airport; 122 mm MRL battalion near Kaemori conducts a short firing exercise.
14:34: North starts firing shells (around 150, of which about 60 land on military positions)
14:38: South conducts emergency sorties with two KF-16 fighters.
14:40: South deploys four F-15K fighters.
14:46: South conducts additional emergency sorties with two KF-16 fighters.
14:47: South fires back with the first round of K-9 howitzers (50 shells).
14:50: South issues a 'Jindogae Hana' (Jindo Dog 1) alert, the highest military alert given for a local provocation.
14:55: North stops firing temporarily.
15:12: North starts firing for the second time (20 shells, all of which landed on the island).
15:25: South resumes firing back with K-9 howitzers (30 shells).
15:30: South telexes the North's military general level talk representative requesting an immediate halt to artillery shelling.
15:40 – 16:00: The South's Joint Chiefs of Staff Han Min-gu and USFK Commander Walter L. Sharp have a video conference (a review of cooperative crisis management).
15:41: North stops firing.
16:30: First military casualty reported.
16:35 – 21:50: Foreign and National Security representatives have a meeting.
16:42: South stops firing.
18:40: Lee Hong-gi, the South's Joint Chief of Staff Director of Operations, holds a press briefing.
19:00: North Korea's Supreme Command of the Korean People's Army releases a statement labelled "Our Army is Making No Empty Talk" publicized through KCNA.
20:35 – 21:10: South Korean President Lee Myung-bak meets with his Joint Chief of Staff.
Aftermath.
Casualties and damage.
The shelling caused a number of casualties among South Koreans living on Yeongpyeong. Two South Korean marines, Hasa (Staff Sergeant) Seo Jeong-wu and Ilbyeong (Lance Corporal) Moon Gwang-wuk, were killed. Six other military personnel were seriously wounded, and ten were treated for minor injuries. Two construction workers, Kim Chi-baek, 61, and Bae Bok-chul, 60, were also killed.
Most of the islanders were evacuated in the aftermath of the shelling. Around 1,500 of the 1,780 residents on the island were taken aboard fishing boats and government vessels, with many of them being taken to Incheon on the mainland. The Incheon city authorities sent 22 fire engines and ambulances to the island, along with firefighters and paramedics, to help with the recovery and relief effort. 2,000 boxes of emergency relief materials and more than 3,500 relief kits and boxes of food were sent to help residents recover.
The attack started widespread fires on the island. According to the local county office, 70 percent of the island's forests and fields were burned and 21 houses and warehouses and eight public buildings were destroyed in the bombardment. Some of the public buildings were formerly military structures, leading the South Korean military to believe the attack was planned from old maps.
North Korea states that it suffered no military casualties. However, Lee Hong-gi, the Director of Operations of the South Korean Joint Chiefs of Staff (JCS), claimed that as a result of the South Korean retaliation "there may be a considerable number of North Korean casualties". A North Korean defector who had served in an artillery battery, however, stated that the South had likely failed to destroy the North Korean artillery batteries due to its slow response. South Korean media reported that 5–10 North Korean soldiers had been killed and 30 wounded, and the National Intelligence Service suggests damage to North Korean troops had been considerable during the South Korean counter-battery fire. Satellite images released by STRATFOR cast doubt on effectiveness of South Korean artillery and damage dealt to North as asserted by JCS and NIS, with no signs of any North Korean rocket