The US and other countries around the world pleaded for restraint today after North Korea fired dozens of artillery shells at a South Korean island, killing two soldiers and injuring civilians. With tensions running high on the peninsula, the South Korean president, Lee Myung-bak, met his top military in an underground bunker in Seoul and ordered the air force to strike North Korean missile bases if there is any further provocation. The clash is one of the most serious since the end of the Korean war in 1953. Relations were already strained by the revelation at the weekend that North Korea has a new uranium enrichment facility. In an immediate response to the artillery barrage, Seoul scrambled F-16 fighter jets to the western sea and returned fire. Diplomats and analysts in Washington and elsewhere around the world warned that while neither the North nor the South wanted all-out war, the risk of incidents such as today’s was that it could tip the peninsula into an accidental war. In his first comments after the attack Barack Obama said the US would defend its ally South Korea but said he would not speculate on possible military options. Robert Gates, the US defence…