From this website:

The post-war years were marked by infrequent but sometimes serious truce violations by the north Koreans. In late 1966, however, north Koreans initiated a campaign of violence that would continue into 1971 and take the lives of more than 40 Americans and hundreds of Koreans -- north as well as south. There was a steady increase in the number of DMZ incidents, terrorist raids, and attempts at subversion in an effort to undermine the growing economic and political stability of the ROK.

Major incidents during this period saw an attempted North Korean commando raid on the Blue House (Presidential Mansion), the USS Pueblo was pirated from international waters, large scale guerrilla incursions occurred on the ROK east coast, and the shooting down of an unarmed U.S. Navy reconnaissance plane-- an EC-121 -- over the Sea of Japan. In the face of the ever-increasing threat, significant improvements were made in the defenders' firepower, mobility, communications and infrastructure. Numerous ROK and U.S. defensive positions were constructed or strengthened. Night observation devices, powerful searchlights and various other sophisticated detection equipment were introduced along the DMZ. The modernization of the ROK Army was accelerated. Concurrently, improvements were made in the Air and Naval components.

The north Korean leaders, with an eye on the growing United States involvement in Southeast Asia, had miscalculated the strength of the allies' resolve to oppose their campaign of hostility. They reverted to a less intense campaign of espionage and subversion. In 1969, north Korea-initiated incidents fell sharply.

Boldface mine.

I have no doubt that in the next several years Iran and others will do their best to undermine the potential for a peaceful Iraq.

They will especially do this if they are convinced that those in charge in the U.S. will capitulate in the face of minimal opposition. One political party in the U.S. has spent five solid years firmly convincing our enemies that if they were in power, they would capitulate immediately, and if they weren't in power, they would do their best to force those in power to capitulate immediately.

It's not polite to bring this up, but sometimes I wonder if the war would have gone better if so many people in the U.S. hadn't been convincing our enemies we would surrender if our enemies would just commit enough violence.