NEW : Joint military exercises are to be held July 25-28 . The meeting will take place in the demilitarized zone . North Korea has been threatening a nuclear strike on South Korea, and it is believed that Pyongyang may have conducted its sixth underground nuclear test last month. North Korea was blamed for the sinking of the warship Cheonan , but denies it .
NEW : Joint military exercises are to be held July 25-28 . The meeting will take place in the demilitarized zone . It is intended to set the stage for higher-level talks . North Korea was blamed for the sinking of the warship Cheonan , but denies it .