The Van Mook Line, also known as the Status Quo Line, named after Hubertus van Mook was an artificial boundary which separated Dutch and the Republic of Indonesia on Java during the Indonesian National Revolution. It was established following the Renville Agreement in January 1948 which ended the first Dutch police action Operatie Product.
The line was surrounded by a no man's land which covered an area about 10–15 km wide. In late 1948, the Republic's military violated the armistice by infiltrating guerrilla forces into Dutch-occupied areas. This prompted the Dutch to launch a second full-scale offensive known as Operatie Kraai in December 1948.
References
Van Mook Line Wikipedia(Text) CC BY-SA