South Korea has reportedly resumed propaganda broadcasts into North Korea amid heightened tensions on the Korean peninsula over the sinking of a South Korean patrol boat on March 26 that left 46 sailors dead.
The resumption of cross-border broadcasts after a break of six years came as Seoul warned it would no longer tolerate provocations from the North after blaming the sinking on a North Korean torpedo attack.
On Tuesday army engineers began installing loudspeakers along the tense border with the North, with plans to also construct 11 giant electronic signboards.
Meanwhile, the South Korean defence ministry said it had resumed FM radio broadcasts on Monday evening, starting with a four-hour programme entitled Voice of Freedom, which was being aired three times a day.
Messages on freedom
A spokesman told the AFP news agency the programme included messages on freedom and democracy from a military anchorwoman, a song from a South Korean girl band extolling freedom of choice, and pointed comments on how obesity rather than hunger is a problem in the South.
The resumption of broadcasts came amid reports that North Korea had ordered its armed forces to be placed on combat alert.
The order came directly from North Korea's leader, Kim Jong-il, South Korea's Yonhap news agency said on Tuesday, quoting sources inside the North.
North Korea has previously threatened "all-out war" in response to any moves to punish it for the sinking.
On Monday United Nations secretary-general joined the US in ratcheting up pressure on North Korea, calling for action from the Security Council in response to the North's alleged torpedo attack on the South Korean patrol ship, the Cheonan.
Speaking at UN headquarters in New York, Ban Ki-moon said there was "overwhelming and deeply troubling" evidence that Pyongyang was behind the sinking in the sea off the west coast of the Korean peninsula.
"My sincere hope is that this will be dealt with by the Security Council, and they should take necessary measures on this matter," Ban said.
"There must be some major step to be taken. The evidence is quite compelling. There is no controversy."
Earlier officials in Washington announced that US forces would conduct joint naval exercises with South Korea "to ensure readiness and to deter future aggression" by North Korea.
|North Korea has warned of "all out war" if it is punished for the sinking [EPA]
Bryan Whitman, a Pentagon spokesman, said the joint exercises would be conducted in the "near future" and would test abilities to defeat submarines and to monitor and prevent illicit activities.
Kim Tae-Young, South Korea's defence minister, said the two countries' navies would soon stage an anti-submarine drill off the west coast.
The display of force comes after last week's findings by a multinational investigation that said the sinking of the Cheonan was the result of a torpedo attack from a North Korean submarine.
The attack was South Korea's worst single military loss of life since the 1950-53 Korean War.
The announcement of the military exercises came after South Korea's president vowed on Monday that North Korea would pay the price for what he called its "brutality" in the sinking.
In a televised address, Lee Myung-bak said: "I solemnly urge the authorities of North Korea ... to apologise immediately to the Republic of Korea (South Korea) and the international community".
He ordered a ban on all trade, investment and visits with North Korea and stopped the North's commercial shipping trade using cheaper routes through waters controlled by the South.
The White House called South Korea's measures to punish the North entirely appropriate and urged Pyongyang to stop its "belligerent and threatening behaviour".
|The March 26 sinking of the Cheonan cost the lives of 46 South Korean sailors [AFP]
The US has some 28,000 troops based in South Korea, while North Korea is believed to have around one million soldiers in what is one of the largest standing armies in the world.
However despite their numbers of personnel, experts say the North's armed forces are poorly equipped and it is unlikely to risk full scale combat against much better armed US and South Korean troops.
Hilary Clinton, the US secretary of state, who is on a visit to China avoided answering a question on whether the US would support additional UN sanctions against North Korea over the sinking.
However, while opening high-level talks in Beijing, Clinton said North Korea must be held to account for the incident.
China is North Korea's only major political and economic backer, and Beijing has avoided firm public comment on the sinking, instead expressing sympathy for the South Koreans killed and urging all sides to show restraint.
Al Jazeera' Beijing correspondent, Melissa Chan, said China had to perform a juggling act, weighing its relationship with North Korea against its ties with the US.
The fact that China has been so cautious shows that it is very worried that the situation could lead to all out war, she said.