(CNN) Sometimes, military tests are meant to see whether weapons systems work. Other times, they're used to make a political point.
A test of long-range artillery Friday by North Korea would seem to fall into the latter category.
Instead of firing on a real target, the North Koreans fired the artillery at "imaginary" targets, including the Blue House, the official residence of the South Korean President, according to a report Friday on North Korean state media KCNA.
On Friday, South Korean President Park Geun-hye gave a speech in Seoul condemning North Korea, saying it continues to engage in "provocations" that South Korea will not accept.
Park said the South Korean military should be ready for any kind of attack from North Korea. She said she would attend the U.S. nuclear safety summit next week to discuss strategies to denuclearize North Korea with world leaders.
Also on Friday, Kim Dong Chul, a Korean-American detained in North Korea, held a new conference in Pyongyang in which he "confessed" to espionage charges, a North Korean official tells CNN.
North Korean official: Korean-American confessed to espionage charges
Kim, 63, first gave details of the alleged spying in an interview with CNN's Will Ripley in Pyongyang in January.