A deadly attack by North Korea on a South Korean island near their disputed border this week sent tensions on the peninsula soaring and set alarm bells ringing around the world.
On November 23, nuclear-armed North Korea fired a barrage of artillery shells on to a South Korean island near their disputed Yellow Sea border in the first such strike since the 1950-53 war.
Two marines and two civilians were killed and 18 people were wounded in the bombardment of the fishing and garrison island of Yeonpyeong, as residents were sent fleeing.
The attack fuelled anxiety about the intentions of the unpredictable communist state, particularly after the disclosure of an apparently operational uranium enrichment plant - a second potential way of building a nuclear bomb.
Most major powers condemned the North Korean attack, with the noticeable exception of Pyongyang's sole major ally Beijing, which merely voiced its "concern" at developments.
On November 24, the United States and South Korea announced plans for four days of war games in the Yellow Sea starting Sunday. US President Barack Obama telephoned South Korean counterpart Lee Myung-Bak telling him that Washington stood "shoulder to shoulder" with Seoul.
South Korea soon suspended shipments of flood aid to the North, while the US-led United Nations Command, which oversees the Korean armistice, called for talks with North Korea but Pyongyang rejects the request.
The foreign minister of China, which was facing pressure from Seoul, Washington and their allies to rein in Pyongyang, cancelled a planned trip to South Korea. Soon after, scores of South Korean protesters burnt the North Korean flag and call for revenge.
On November 25, South Korea's defence minister Kim Tae-Young resigned amid strong criticism that the military reacted feebly to the shelling, which followed the sinking of one of Seoul's warship in March blamed on Pyongyang.
Seoul announced that it would send more troops and guns to frontline islands in the Yellow Sea and bolster its rules of engagement, while North Korea warned of more strikes if it continues to face a "reckless military provocation" from the South.
On friday however, North Korea warned further that plans for a US-South Korean naval exercise was bringing the peninsula "closer to the brink of war."
Seoul maintains that the North appeared to have staged an artillery firing exercise in the Yellow Sea, sending residents of the island of Yeonpyeong rushing into air raid shelters.