North and South Korea 'trade artillery fire in border zone'
The South Korean military said it has returned fire after North Korea shot an artillery shell at a border town.
The South's defence ministry said its surveillance equipment detected a single North Korean shell fired across the border.
Officials said South Korea fired dozens of shells at the location of that North Korean shell.
There are no other immediate details, including reports of what happened in the South Korean town.
The North had previously said it would retaliate for South Korean broadcasts critical of alleged North Korean provocations and trumpeting the South's democratic system.
Seoul began airing the broadcasts recently in response to what it said were North Korean land mines that maimed two South Korean soldiers.