A North Korean broadcast of numbers on June 24 ended a 16-year sojourn that is surprising many who thought Pyongyang had given up on the old spy trick.

The practice was halted in 2000 after the first inter-Korea summit between North Korean President Kim Jong-Il and South Korean President Kim Dae Jun.

The 14-minute broadcast of two sets of numbers by a female voice appears to have been the work of the Voice of Korea (formerly Radio Pyongyang), a North Korean radio propaganda station that broadcasts accolades of the Kim family.

A retired US National Security Agency source said the fact it was a 10-11 meter frequency band in the middle of the night, considering that North Korea does not have relay stations like many other shortwave stations, would make the target local to South Korea, Japan or northern China.