JUDY WOODRUFF: Next: new tensions on the Korean Peninsula and what they look like to people in the South. Southern forces continued their military exercises today, and leaders in both countries stepped up their rhetoric.
A high-ranking North Korean defense official talked of war.
KIM YONG CHUN, North Korean defense official (through translator): The armed forces of the DPRK are getting prepared to launch a sacred war of justice, Korean-style, using the nuclear deterrent any time it is necessary to cope with the enemy's actions, which are deliberately pushing the situation to the brink of war.
JUDY WOODRUFF: South Korea's president said his country would make an unsparing response if attacked.
We have a sampling of public opinion in Seoul. It comes from Justin McCurry of our international reporting partner, GlobalPost.
JUSTIN MCCURRY, GlobalPost: Air raid sirens warn of an impending attack on the South Korean capital, Seoul -- the source of the threat, North Korea.
Fortunately, it is only a drill. But, as residents of a city just 27 miles from the border with North Korea, the people of Seoul are accustomed to preparing for the worst. This recent civil defense exercise was the largest in years. Traffic was brought to a halt, and people were ordered into 25,000 shelters across the country.
It is a rehearsal for what South Koreans fear most: a surprise attack from North Korea, and the start of another bloody conflict almost 60 years after civil war saw the countries separated by the most heavily fortified border in the world.
The North has been showing increased signs of aggression. In March, it sunk a South Korean navy vessel called the Cheonan, killing 46 sailors. And, in November, it shelled Yeonpyeong Island, a South Korean territory close to the countries' disputed maritime border in the Yellow Sea.
On the streets of Seoul, fears of an attack have magnified, and there seems to be little appetite for dialogue with the Pyongyang regime.
MAN (through translator): The attacks were nonsensical. The North Koreans are supposed to be our fellow countrymen, so what they did, as our brothers, was morally indefensible. They have showed their real communist face, and we can no longer trust them.
JUSTIN MCCURRY: On Monday, the South conducted live-fire drills on Yeonpyeong Island, but the North never made good on its threat to retaliate, leading some to believe that tensions may be easing.
Still, many residents of Seoul have been critical of what they see as their government's lack of a coherent approach towards dealing with its saber-rattling neighbor.
MAN (through translator): Every time the South Korean government changes, our policy toward the North changes. We need a consistent, non- partisan solution to avoid more confusion and relieve the tension.
JUSTIN MCCURRY: But others here think the South needs less talk and more force. South Korean President Lee Myung-Bak was initially criticized by some for his seemingly weak-kneed response to the attacks. But he has since vowed to call in immediate airstrikes should the North attack again.
MAN (through translator): I agree with the hard-line stance taken by Lee Myung-Bak. The hawkish way is the only one that will bring results. We need to retaliate strongly against the North.
JUSTIN MCCURRY: North Korean Leader Kim Jong Il has indicated he is preparing to hand over power to his youngest son, Kim Jong-un.
Analysts say the North is acting provocatively to burnish their leader-in-waiting's military credentials and to win diplomatic concessions from the U.S.
At Tebuk Yong-ok (ph), a restaurant in Seoul, North Korean defectors share their insights in the attack launched by a country they fled to make a new life in the South.
Kim Heung Kwang left North Korea in 2002.
KIM HEUNG KWANG, president, North Korean Intellectuals Society (through translator): North Korea was confident it was a clever ploy, that Washington and Seoul would give it the aid it needs to stop the provocations.
But the reaction has not been what it anticipated. Because it is not getting what it wants, it is pestering other countries. North Korea wants Washington to make this issue a foreign policy priority, so its recent behavior was designed to send a message to the U.S., South Korea and international society.
JUSTIN MCCURRY: Kim Chul-woong, a professional pianist who played with North Korea's prestigious State Symphony Orchestra, fled the country eight years ago to realize his dream of becoming a jazz musician. He thinks the way to manage the problem is to bring in the region's most influential player.
KIM CHUL-WOONG, North Korean defector (through translator): China, in particular, should stop thinking about how it can benefit from propping up North Korea. It should be more interested in long-term peace than in how it can protect its own interests. China should play a proper role as a mediator.
JUSTIN MCCURRY: But Lee Hye-kyung, a pharmacist who also fled from the North, wants to see the South Korean government act decisively if faced with further provocations.
LEE HYE-KYUNG, North Korean defector (through translator): South Korea has behaved like a vending machine for the North over the past 10 years. Whenever the North demanded a certain amount of cash, the South automatically said yes and gave it what it needed. All it had to do was push the vending machine's button and pocket the money.
JUSTIN MCCURRY: But with tensions at current levels, the South Korean government is faced with its strongest test in decades of how to deal with its neighbor to the north.
JUDY WOODRUFF: Tomorrow night, we will have a newsmaker interview with Governor Bill Richardson of New Mexico about his recent visit to North Korea.