From the Summary: "This selective list of events provides information on instances of North Korean provocative actions between June 1950 and 2007. The purpose of this report is to place current provocations in the context of past actions to better judge their significance and to determine changes in trends. The term "provocation" is defined to include armed invasion; border violations; infiltration of armed saboteurs and spies; hijacking; kidnapping; terrorism (including assassination and bombing); threats/intimidation against political leaders, media personnel, and institutions; incitement aimed at the overthrow of the South Korean government; actions undertaken to impede progress in major negotiations; and tests of ballistic missiles and nuclear weapons. Information in this report was taken from South Korean and Western sources, but typically is denied by the North Korean government. The most intense phase of the provocations was in the latter half of the 1960s, when North Korea (Democratic People's Republic of Korea, or DPRK) staged a series of limited armed actions against South Korean and U.S. security interests. Infiltration of armed agents into South Korea was the most frequently mentioned type of provocation, followed by kidnapping and terrorism (actual and threatened)."
CRS Report for Congress, RL30004