South Korea said on Friday it would bomb North Korea if it tries a repeat of last week's attack, with the United States warning of an "immediate threat" from Pyongyang.
Kim Kwan, a retired general, was speaking at a parliamentary meeting confirming him as new defence minister, a day after U.S. Secretary of State Hillary Clinton said North Korea threatened the region and the world.
"If there are further provocations, we will definitely use aircraft to bomb North Korea," Mr. Kim said, when asked how he would respond to another attack after last week's North Korean bombardment of an island near their disputed border, killing two South Korean marines and two civilians.
For nearly 60 years, the two Koreas have faced each other across one of the world's most heavily armed borders. They have never signed a peace treaty to end the 1950-53 Korean War.
The North alone has more than 5,000 multiple-launch rockets pointed at the capital Seoul which, with its satellite cities, is home to some 25 million people.
The foreign ministers of the United States, Japan and South Korea, long-time allies, meet in Washington on Monday to discuss North Korea.
North Korean ally China, pushing for an emergency meeting of the six countries involved in denuclearization talks, is not going. That means the discussions in Washington have little chance of breaking the impasse within the international community on a common approach to deal with the mounting tension on the Korean peninsula.
South Korea's foreign ministry said a joint statement criticizing North Korea's shelling of South Korea was being prepared. Japan's Mainichi newspaper said the statement would call on North Korea to stop provocative actions and enrichment of uranium - a second way for it to produce material for nuclear weapons.
U.S. and Japanese forces began manoeuvres on Friday, adding to tension. The exercises will involve about 44,500 personnel.
Japanese Defence Minister Toshiba Kitazawa described the manoeuvres as "normal training" held every two years.
"Changes in the regional security situation are naturally taken into consideration," he said. "But this is not something that is targeted at any particular country."
Ms. Clinton said: "North Korea poses an immediate threat to the region around us, particularly to South Korea and Japan.
"It poses a medium-term threat if it were to collapse to China, because of refugees and other instability. And it poses a long-term threat to the entire world, because of its nuclear program, and its export of weapons around the world."
South Korea had exercised great restraint, she said in the Kyrgyz capital Bishkek, according to a transcript released by the U.S. State Department.
The United States has been pushing China, North Korea's only major ally, to bring the reclusive country to heel. China has refused to blame North Korea for last week's attack, or for the earlier sinking of a South Korean naval vessel. A team of international investigators said the North torpedoed the ship.
On Wednesday, South Korea's spy chief said it was highly likely the North would attack its wealthy neighbour again.
China, which said it would not play favourites in the dispute, has proposed emergency talks of the two Korea, China, Japan, Russia and the United States. Only Russia has given its support.
Chinese Foreign Ministry spokeswoman Kiang Yup responded to criticism that China was not doing enough with a thinly disguised slap at the U.S.-South Korea military manoeuvres.
"Those who brandish weapons are seen to be justified, yet China is criticized for calling for talks. Is that justified?"
Six-party talks aimed at ending North Korea's nuclear program were suspended in December 2008 after North Korea walked out.